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Classifications

Harrison's Chapter

ICD-O Morphology

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Mappings

MONDO

MONDO:0017895 familial papillary or follicular thyroid carcinoma Not Yet Curated

MONDO:0017895 ("familial papillary or follicular thyroid carcinoma", exact synonyms FNMTC and "familial nonmedullary thyroid gland carcinoma") is a direct child of MONDO:0017896 that it effectively duplicates, and MONDO itself tags it with `subset: obsoletion_candidate`. This entry therefore anchors `disease_term` on the parent MONDO:0017896 and records MONDO:0017895 as a close match rather than as a separate disease identity. The distinction MONDO:0017895 nominally adds - restricting to papillary or follicular histology - is not a real narrowing, because papillary and follicular carcinoma together constitute essentially all non-medullary thyroid carcinoma in familial series. Note that neither term cleanly hosts a syndromic-inclusive umbrella: MONDO:0017895 is an obsoletion candidate, and MONDO:0017896 is itself defined as "a rare non-syndromic form of thyroid cancer" and carries `subset: disease_grouping` / `subset: ordo_group_of_disorders`. Anchoring here is therefore the least bad option rather than an exact fit, which is why this entry scopes itself to the non-syndromic form and models the syndromic causes as differential diagnoses; see the `fnmtc-mondo-granularity` discussion.

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Inheritance

2

Polygenic Susceptibility HP:0010982

Non-syndromic FNMTC is most commonly modeled as a polygenic trait in which multiple low- to moderate-penetrance susceptibility alleles combine to raise thyroid carcinoma risk, rather than as a single high-penetrance Mendelian locus. The best-replicated contributors are common GWAS risk alleles near FOXE1 (9q22.33) and NKX2-1 (14q13.3), each of modest individual effect. This inheritance model is why no validated predictive gene panel exists for isolated non-syndromic kindreds. Family-specific oligogenic combinations of rare alleles are a plausible alternative model for individual pedigrees but are not established as a general mechanism; see the open discussion on genetic architecture below.

Polygenic inheritance Penetrance: INCOMPLETE Expressivity: VARIABLE

Show evidence (5 references)

PMID:33025555 SUPPORT Human Clinical

"FNMTC is described as a polygenic disorder associated with multiple low- to moderate-penetrance susceptibility genes and incomplete penetrance."

Directly supports the polygenic, low-to-moderate-penetrance model with incomplete penetrance.

PMID:35295987 SUPPORT Human Clinical

"Non-syndromic familial non-medullary carcinoma has a complex and heterogeneous genetic basis involving several genes and loci with a monogenic or polygenic inheritance model."

Supports genetic heterogeneity with a polygenic (as well as monogenic) inheritance model.

PMID:37175550 SUPPORT Human Clinical

"Although no common mutated genes were detected, biological processes regulating functions such as cell proliferation, differentiation, survival and adhesion were enriched."

Contemporary whole-exome evidence (58 individuals from 18 families) for locus heterogeneity - no recurrent gene emerged, which is what the polygenic model predicts.

+ 2 more references

Autosomal Dominant Susceptibility With Reduced Penetrance HP:0000006

Many individual kindreds segregate apparent autosomal-dominant susceptibility with reduced, age-dependent penetrance and variable expressivity. This pedigree-level pattern coexists with, rather than contradicts, the polygenic model: it is what a small number of rare moderate-penetrance alleles on a polygenic background looks like in a single large family, and it is the model under which the classic linkage loci (TCO, fPTC-PRN, NMTC1) were mapped.

Autosomal dominant inheritance Penetrance: INCOMPLETE Expressivity: VARIABLE

Show evidence (2 references)

PMID:33488516 SUPPORT Human Clinical

"show an autosomal dominant pattern of inheritance with incomplete penetrance and variable expressivity"

States the autosomal-dominant-with-incomplete-penetrance model for FNMTC kindreds.

PMID:9837827 SUPPORT Human Clinical

"The transmission of susceptibility to FNMTC is compatible with autosomal dominant inheritance with reduced penetrance, or with complex inheritance."

The linkage study that mapped TCO states the dominant-with-reduced-penetrance (or complex) transmission model.

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Subtypes

5

Non-Syndromic (Isolated) Familial Non-Medullary Thyroid Carcinoma

The default form and the main subject of this entry - follicular-cell thyroid cancer in two or more first-degree relatives with no recognised tumour-predisposition syndrome and no identified environmental cause. No validated major susceptibility gene exists and the working model is polygenic. The subtypes below are the named linkage loci and the one molecularly defined subset carved out of this group; the recognised syndromic causes are modelled as differential diagnoses rather than subtypes, per this entry's scoping decision - with the single principled exception of the long-telomere shelterin subtype, which is syndromic in tumour spectrum but is not recognisable before testing and was carved directly out of non-syndromic-ascertained cohorts. No `subtype_term` is bound on this root subtype: the entry's own `disease_term`, MONDO:0017896, is itself defined as the non-syndromic form, so binding the same term here would be circular rather than informative.

Show evidence (1 reference)

PMID:26222560 SUPPORT Human Clinical

"Nonsyndromic familial nonmedullary thyroid cancer accounts for more than 95% of all cases of familial nonmedullary thyroid cancer."

Establishes the non-syndromic form as the numerically dominant one.

TCO - Thyroid Tumours with Cell Oxyphilia (19p13.2) MONDO:0011312

A non-syndromic FNMTC entity defined in a French pedigree with multinodular goitre and non-medullary thyroid carcinoma in which both benign and malignant thyroid tumours show oxyphilic (Hurthle/oncocytic) cell change. Mapped by linkage to 19p13.2 and named TCO; the causal gene has not been identified.

Show evidence (2 references)

PMID:9837827 SUPPORT Human Clinical

"TCO was mapped to chromosome 19p13.2 by linkage analysis with a whole-genome panel of microsatellite markers."

Establishes the TCO locus assignment.

PMID:9837827 SUPPORT Human Clinical

"Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC."

Defines the oxyphilic histologic signature distinguishing this subtype.

fPTC/PRN - Familial Papillary Thyroid Carcinoma with Papillary Renal Neoplasia (1q21) MONDO:0011578

A distinct heritable tumour syndrome characterised by the familial association of papillary thyroid carcinoma, nodular thyroid disease and papillary renal neoplasia, mapped by linkage to 1q21 in a large three-generation kindred. MET, the gene of isolated familial papillary renal neoplasia, was excluded by both linkage and sequencing.

Show evidence (2 references)

PMID:10843148 SUPPORT Human Clinical

"A distinct inherited tumor syndrome has been characterized as the familial association of papillary thyroid cancer, nodular thyroid disease, and papillary renal neoplasia."

Defines the fPTC/PRN phenotype.

PMID:10843148 SUPPORT Human Clinical

"A genome-wide screening and an investigation of specific candidate genes demonstrated that the fPTC/PRN phenotype was linked to 1q21."

Establishes the 1q21 locus assignment.

NMTC1 - Familial Non-Medullary Thyroid Carcinoma Susceptibility Locus (2q21) MONDO:0008567

A susceptibility locus mapped to 2q21, first through a shared haplotype in a large Tasmanian papillary thyroid carcinoma pedigree and then replicated by linkage in 80 independent pedigrees. The signal strengthened markedly when pedigrees were stratified for the follicular variant of papillary thyroid carcinoma, suggesting NMTC1 predisposes specifically to follicular-patterned tumours. The causal gene has not been identified.

Show evidence (2 references)

PMID:11438887 SUPPORT Human Clinical

"These results indicate the existence of a susceptibility locus for familial NMTC on chromosome 2q21."

Establishes the NMTC1 locus assignment.

PMID:11438887 SUPPORT Human Clinical

"Stratification based on the presence of at least one case of the follicular variant of PTC, the phenotype observed in the Tas1 family, identified 17 such pedigrees, yielding a maximal HLOD score of 4.17 (alpha=0.80) and NPL=4.99 (P=.00002) at markers AFMa272zg9 and D2S2271, respectively."

Documents the follicular-variant stratification that sharpens the 2q21 signal.

Telomere-Lengthening (POT1/TINF2/ACD) Syndromic Papillary Thyroid Cancer

POT1 hgnc:17284 TINF2 hgnc:11824 ACD hgnc:25070

The one molecularly defined subset so far carved out of non-syndromic FNMTC - germline shelterin (POT1, TINF2, ACD) variants producing ultra-long telomeres and predisposing to papillary thyroid cancer alongside melanoma, lymphoma and sarcoma. Found in 4.5% of familial cases, and in 22% of individuals with both papillary thyroid cancer and melanoma, which makes the combination clinically recognisable. Directionally opposite to the telomere-shortening/fragility model in the pathograph above; both are curated so the tension is visible, and both are now separable at the pathograph level under the `telomere_length_predisposition` hypothesis group rather than only in prose. Note the apparent tension with the scoping rule stated on Non-Syndromic FNMTC: this subtype IS syndromic in its tumour spectrum, but unlike FAP, Cowden, Carney, Werner and DICER1 it is not recognisable before testing and was carved directly out of cohorts ascertained as non-syndromic FNMTC, so it belongs here as a subtype rather than as a differential. No `subtype_term` is bound: MONDO has no generic term for the long-telomere / shelterin papillary thyroid cancer syndrome, only gene-specific terms (e.g. MONDO:0100570 for POT1 tumour predisposition) that would under-represent a three-gene entity. Left deliberately unbound rather than mis-bound; a candidate MONDO NTR.

Show evidence (2 references)

PMID:38688277 SUPPORT Human Clinical

"Among individuals with PTC and melanoma, 22% carried a deleterious germline variant, suggesting that a long telomere syndrome might be clinically recognizable."

Gives the clinically actionable PTC-plus-melanoma recognition rule.

PMID:38688277 SUPPORT Human Clinical

"Individuals harboring these variants had ultra-long telomere length, and 15 of 18 (83%) developed other cancers, of which melanoma, lymphoma, and sarcoma were most common."

Establishes the ultra-long-telomere phenotype and associated tumour spectrum.

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Mechanistic Hypotheses

3

HABP2 p.G534E as an FNMTC susceptibility allele

habp2_g534e_susceptibility ⚠ DEPRECATED

⚠ Overturned model — shown for reference, not as current mechanism

DisMech records superseded hypotheses explicitly rather than deleting them, so that claims still circulating in reviews, textbooks and older diagnostic criteria can be checked against an assessment. This model is not part of the disease mechanism DisMech asserts.

Citation volume does not decide standing here. A hypothesis may retain more supporting than refuting citations simply because the supporting literature accumulated for decades before the refutation landed; where the two conflict, DisMech follows the more recent and more direct evidence. Supporting citations below are retained for the historical record.

Evidence balance 1 support 2 refute

Proposed in 2015 on the basis of cosegregation in a single kindred, enrichment in TCGA papillary thyroid cancers (4.7% versus 0.7%), and dominant-negative functional assays; supported in one independent kindred series. Contradicted by at least four independent replication studies on three grounds: failure of cosegregation within families carrying the variant, population carrier frequencies of 7.6-9.3% incompatible with a high-penetrance allele, and absence of HABP2 expression in thyroid tissue. Marked DEPRECATED because the weight of replication is against a causal role and contemporary reviews treat G534E as a common polymorphism or a private variation rather than an FNMTC gene. Retained explicitly rather than deleted, because the controversy is itself instructive and the supporting reports remain in the literature. The narrow residual question - whether the allele could act as a very-low-penetrance modifier in some ancestries - is tracked in the fnmtc-habp2-controversy discussion.

Pathograph links

Inherited Non-Syndromic Susceptibility in Thyroid Follicular Cells -> HABP2 G534E Loss of Tumor-Suppressor Function DIRECT Contested branch - proposed as the germline lesion in one kindred but not replicated. Modelled only under the DEPRECATED habp2_g534e_susceptibility hypothesis group.

HABP2 G534E Loss of Tumor-Suppressor Function -> Multifocal Follicular Cell Transformation UNKNOWN Proposed but unreplicated route from HABP2 loss of function to malignant transformation of the follicular epithelium.

Show evidence (3 references)

PMID:26222560 SUPPORT Human Clinical

"Our findings suggest that HABP2 is a susceptibility gene for thyroid cancer of follicular-cell origin."

The originating claim.

PMID:26745718 REFUTE Human Clinical

"Given these results showing lack of any involvement we suggest that the putative role of variant HABP2 in PTC should be carefully scrutinized."

The most-cited refutation.

PMID:26906432 REFUTE Human Clinical

"In this study, HABP2 mutations were not found in familial NMTC, and the G534E variant is not the underlying genetic defect in a large sample of sporadic NMTC from the Middle East."

Independent non-replication in a large familial and sporadic series.

Germline telomere-length dysregulation as an FNMTC predisposition mechanism

telomere_length_predisposition EMERGING

Evidence balance 1 support 2 partial

Two directionally opposite versions of a telomere hypothesis coexist in this entry and are deliberately both curated. The older version holds that familial papillary thyroid cancer patients carry SHORTER germline and somatic telomeres with hTERT amplification and excess spontaneous telomeric associations and fusions - the constitutional chromosome-fragility arm modelled by the Telomere-Telomerase Imbalance and Chromosome Fragility node; support is inconsistent, with at least one study finding no difference between familial and sporadic cases. The newer and better-powered version holds that germline LENGTHENING variants in the shelterin proteins POT1, TINF2 and ACD define a syndromic long-telomere papillary thyroid cancer subtype present in 4.5% of familial cases, with the mechanism being an expanded replicative reserve. The two point in opposite directions but are not strictly incompatible: shelterin variants account for only a small minority of familial cases, so the two literatures may simply describe different subgroups. Status EMERGING because the relationship is unresolved.

Pathograph links

Inherited Non-Syndromic Susceptibility in Thyroid Follicular Cells -> Telomere-Telomerase Imbalance and Chromosome Fragility INDIRECT UNKNOWN INTERMEDIATES Familial cases show a constitutional telomere-telomerase imbalance whose causal genes are not identified, so the link is indirect.

Telomere-Telomerase Imbalance and Chromosome Fragility -> Acquisition of Somatic MAPK-Activating Driver Alterations INDIRECT UNKNOWN INTERMEDIATES Constitutional telomeric instability plausibly raises the rate at which follicular cells acquire and fix oncogenic somatic alterations.

Show evidence (3 references)

PMID:38688277 SUPPORT Human Clinical

"We tested whether variants in POT1 and four other telomere-maintenance genes associated with familial cancer underlie PTC susceptibility."

The telomere-lengthening arm of the hypothesis.

PMID:33025555 PARTIAL Human Clinical

"Some studies have demonstrated that FNMTC patients have shorter germline and somatic telomere length suggesting the role of telomere shortening in the development of FNMTC"

Records the older telomere-SHORTENING arm, which reports the opposite direction of effect from the shelterin literature.

PMID:33025555 PARTIAL Human Clinical

"However, another study did not shown any differences in telomere length and telomerase activity between familial and sporadic PTC cases"

Records the inconsistency within the telomere-shortening arm itself.

Genetic anticipation in FNMTC across generations

clinical_anticipation ALTERNATIVE

Evidence balance 3 support 1 partial

Several series report that the second generation of parent-child FNMTC kindreds presents at an earlier age, with more multifocal and bilateral tumours, more nodal metastases and worse outcome than the first generation, and a six-study meta-analysis confirms a younger age of onset in the second generation. No repeat expansion or other molecular anticipation mechanism has been demonstrated; the one candidate substrate is progressive intergenerational telomere lengthening in shelterin-variant kindreds, which applies to only a small minority of families. The competing explanation is structural: once a parent is diagnosed, offspring enter surveillance and are therefore diagnosed earlier and at smaller size by construction, and prospective screening data confirm that this mechanism operates. Curated as ALTERNATIVE and never CANONICAL - the observation is real, but its interpretation as true genetic anticipation is not established.

Pathograph links

Multifocal Follicular Cell Transformation -> Earlier Age at Onset in Successive Generations INDIRECT UNKNOWN INTERMEDIATES Observed clinical anticipation, at least partly confounded by ascertainment and surveillance intensity.

Show evidence (4 references)

PMID:18832444 SUPPORT Human Clinical

"In conclusion, FNMTC displays the features of clinical 'anticipation' with the second generation acquiring the disease at an earlier age and having more advanced disease at presentation."

The originating observation of clinical anticipation in FNMTC.

PMID:28942234 SUPPORT Human Clinical

"Thus we conclude that the second generation of parent/offspring type FNMTC patients is in higher risk than their first generation counterpart."

Meta-analytic confirmation of the generational difference.

PMID:38688277 SUPPORT Human Clinical

"Successive generations had longer telomere length than their parents and, at times, developed more cancers at younger ages."

The only reported molecular substrate that could make anticipation genuine in a subset of families - progressive intergenerational telomere lengthening, distinct from a repeat expansion.

+ 1 more reference

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Discussions and Knowledge Gaps

5

Does germline HABP2 p.G534E confer susceptibility to familial nonmedullary thyroid carcinoma in any subset of kindreds, or should the association be considered refuted outright?

CONTROVERSY OPEN fnmtc-habp2-controversy

Attached to

genetic#HABP2

The 2015 New England Journal of Medicine report of germline HABP2 p.G534E cosegregating in a large FNMTC kindred, supported by loss-of-function assays, was the highest-profile candidate-gene claim in this field. It was contradicted within a year on two independent grounds: failure of cosegregation in other kindreds carrying the allele, and an allele frequency of 7-9% in unselected populations, which is incompatible with a highly penetrant dominant cancer allele. Independent European series are likewise negative. The dismech entry therefore types HABP2 as DISPUTED and carries both the original SUPPORT evidence and the REFUTE evidence, so downstream consumers see the controversy rather than a one-sided assertion. The residual open question is whether the variant could act as a very-low-penetrance modifier in some ancestries - a hypothesis that current data neither establish nor formally exclude - not whether it is a clinically actionable predisposition allele, which it is not.

Proposed experiments

Ancestry-matched case-control association testing of HABP2 p.G534E

fnmtc-exp-habp2-casecontrol

Ancestry-matched case-control association testing of HABP2 p.G534E at sufficient power to detect an odds ratio below 1.3.

Formal cosegregation meta-analysis across all published FNMTC

fnmtc-exp-habp2-cosegregation

Formal cosegregation meta-analysis across all published FNMTC kindreds carrying the allele.

What is the genetic architecture of non-syndromic FNMTC - polygenic accumulation of common low-effect alleles, family-specific oligogenic combinations of rare alleles, or a set of as-yet-unidentified moderate-penetrance monogenic causes?

KNOWLEDGE GAP OPEN fnmtc-genetic-architecture

Attached to

pathophysiology#Inherited Non-Syndromic Susceptibility in Thyroid Follicular Cells

The susceptibility genes for roughly 95% of FNMTC cases remain uncharacterized despite three decades of linkage, GWAS and exome/genome sequencing. Reviews describe the trait as polygenic with multiple low- to moderate-penetrance genes, yet individual kindreds segregate apparent autosomal dominance and each family tends to carry its own candidate lesion. These three models are not mutually exclusive and cannot currently be distinguished, which is why no predictive gene panel exists for isolated kindreds. This entry asserts the polygenic and autosomal-dominant-with-reduced-penetrance models, for which quotable evidence exists, and deliberately does NOT bind an oligogenic inheritance term (HP:0010983), because no cited source demonstrates joint transmission of two or more specified loci in an FNMTC pedigree.

Proposed experiments

Polygenic risk score construction from thyroid cancer

fnmtc-exp-prs-multiplex

Polygenic risk score construction from thyroid cancer GWAS loci, tested for enrichment in multiplex FNMTC kindreds versus matched sporadic cases.

Large-scale trio and multiplex-family whole-genome sequencing with

fnmtc-exp-wgs-multiplex

Large-scale trio and multiplex-family whole-genome sequencing with joint linkage and rare-variant burden analysis across ancestries.

Systematic testing for two-locus joint transmission in

fnmtc-exp-two-locus-transmission

Systematic testing for two-locus joint transmission in kindreds carrying more than one candidate rare allele, which would be required before an oligogenic inheritance term could be asserted.

Is the reported clinical anticipation and increased aggressiveness of familial tumors a biological property of FNMTC, or an artefact of ascertainment and intensified surveillance of known families?

CONTROVERSY OPEN fnmtc-aggressiveness-ascertainment

Attached to

phenotype#Earlier Age at Onset in Successive Generations

Multiple independent series report earlier onset, more multifocality and bilaterality, and higher nodal metastasis rates in second-generation affected relatives, and matched case-control studies find increased biological aggressiveness. But once a family is identified, its younger members are imaged more intensively and earlier, which by itself produces earlier apparent age at diagnosis and smaller detected tumors. No repeat-expansion or other molecular anticipation mechanism has been demonstrated. Critically, the largest contemporary series finds a more aggressive presentation that does not translate into a worse outcome - the pattern one expects from detection bias plus effective treatment, and the reason major guidelines have not endorsed escalating surgery or universal relative screening on the basis of family history alone.

Proposed experiments

Prospective screening-protocol-matched comparison of familial and sporadic

fnmtc-exp-screening-matched-cohort

Prospective screening-protocol-matched comparison of familial and sporadic cohorts, with lead-time and length-time bias correction.

Registry-based analysis of familial versus sporadic outcomes

fnmtc-exp-registry-detection-mode

Registry-based analysis of familial versus sporadic outcomes stratified by whether the index case was detected by family screening or by symptoms.

Decision criterion

Attenuation of the familial-versus-sporadic difference within the symptom-detected stratum would indicate the effect is substantially a product of detection mode rather than of tumour biology.

Prospective parent-offspring germline telomere-length measurement

fnmtc-exp-parent-offspring-telomere-length

Measure germline leukocyte telomere length prospectively in parent-offspring pairs within the same FNMTC kindreds, to test the one proposed molecular substrate for anticipation directly and to reconcile the telomere-shortening and telomere-lengthening literatures collected under the telomere_length_predisposition hypothesis group.

Decision criterion

A systematic intergenerational change in telomere length that tracks age at diagnosis would supply the missing molecular substrate and move the clinical_anticipation hypothesis off ALTERNATIVE; no such gradient would leave ascertainment as the parsimonious explanation.

Show evidence (6 references)

PMID:25637073 SUPPORT Human Clinical

"FNMTC possessed more aggressive biological behaviors, characterized by younger age at diagnosis (SMD=-0.91, 95% CI: -1.59 to -0.22), higher risk of multifocal (OR=1.50, 95% CI: 1.32 to 1.71), bilateral (OR=1.29, 95% CI: 1.00 to 1.66), extrathyroidal invasion (OR=1.20, 95% CI: 1.02 to 1.41), and..."

Pooled effect sizes for the "more aggressive presentation" side of the controversy, across 12 studies and 12,741 participants.

PMID:25637073 SUPPORT Human Clinical

"FNMTC patients had an increased rate of recurrence (OR=1.72, 95% CI: 1.34 to 2.20) and decreased disease-free survival (DFS) (HR=1.83, 95% CI: 1.34 to 2.52) in comparison with SNMTC patients."

The strongest quantitative claim that the presentation difference does translate into a worse outcome - the counter to the detection-bias reading.

PMID:40908394 SUPPORT Human Clinical

"The clinical aggressiveness of FNMTC escalates with increasing numbers of affected family members."

2025 meta-analysis of 3,036 FNMTC and 10,497 sporadic patients showing a dose-response with pedigree size. A dose-response is harder to explain by detection bias alone and is the strongest argument for a real biological component.

+ 3 more references

Which MONDO term should host FNMTC, and should the entity that hosts it include the syndromic forms or only the non-syndromic (pure) form?

INTERPRETATION OPEN fnmtc-mondo-granularity

Neither available MONDO term is a clean fit, and the mismatch is worth recording rather than papering over. MONDO:0017895 ("familial papillary or follicular thyroid carcinoma") carries `subset: obsoletion_candidate`, is a direct child of MONDO:0017896 that it effectively duplicates, and takes the Orphanet synonym "familial pure nonmedullary thyroid carcinoma", which reads as the non-syndromic form specifically. The obvious fallback does NOT resolve the mismatch either: MONDO:0017896 is itself defined as "a rare non-syndromic form of thyroid cancer" and carries `subset: disease_grouping` / `subset: ordo_group_of_disorders`, so anchoring there still excludes the syndromic forms and additionally anchors a Disease entry on a grouping term. This entry takes option (b) below: it anchors `disease_term` on MONDO:0017896, scopes itself to the non-syndromic form, keeps MONDO:0017895 as a skos:closeMatch, and models the recognised syndromic causes (APC, PTEN, PRKAR1A, WRN, DICER1) as differential_diagnoses plus typed `genetic` entries that point at their own full dismech entries, rather than as has_subtypes of this one. The genuine options are (a) treat this entry as a clinical umbrella carrying both non-syndromic loci and syndromic forms as has_subtypes, matching how the clinical literature partitions FNMTC but contradicting both MONDO definitions; (b) the scoping used here; or (c) model the clinical umbrella as a dismech Grouping over the existing syndromic disease entries plus this non-syndromic Disease entry, which is exactly what the Grouping class exists for. Option (c) is probably the right long-term answer but is a lump-versus-split judgement that should be made once, deliberately, for the whole hereditary-cancer area rather than unilaterally here - flagging for human adjudication by @cmungall.

Is the conventional two-affected-first-degree-relative definition of FNMTC fit for purpose, or should the threshold be three?

OPEN QUESTION OPEN fnmtc-two-relative-definition

Attached to

diagnosis#Pedigree-Based Clinical Definition

This is not a terminological quibble - it silently determines every statistic in this entry, because a cohort assembled under the two-relative rule is diluted with coincidental clusters and will understate any true familial effect. For raising the threshold: a probability argument (Charkes) concludes that 62-69% of two-case families are coincidental sporadic clustering; prospective screening yield tracks the same gradient, at 4.6% cancer detection in two-case families versus 22.7% in families with three or more affected members; and a 2025 meta-analysis finds that clinical aggressiveness escalates with the number of affected relatives, proposing that three-or-more-case families be treated as a distinct high-risk subgroup. Against raising it: population-registry data show that more than 90% of familial cancer clusters contain only two affected members, so a three-relative rule would exclude most genuinely low-penetrance familial disease - precisely the disease that the polygenic model predicts should dominate. The definition used in this entry remains two or more first-degree relatives, matching the clinical literature, with the dilution caveat carried explicitly here and in the Pedigree-Based Clinical Definition diagnosis entry.

Proposed experiments

Pedigree-size-stratified reanalysis of pooled FNMTC cohorts

fnmtc-exp-pedigree-size-stratified-reanalysis

Reanalyse pooled familial cohorts with every outcome reported separately for two-case and three-or-more-case kindreds, rather than pooling them under a single FNMTC label.

Decision criterion

If effect estimates in two-case families collapse toward the sporadic null while three-or-more-case families retain them, the two-relative definition is diluting the entity and the threshold should be raised for research use even if retained clinically.

Show evidence (4 references)

PMID:33025555 SUPPORT Human Clinical

"According to his mathematical simulation, 62–69% of 2-hit families are sporadic occurrences and thus, only families with 3 or more affected first-degree relatives should be considered for clinical and genetic investigations of FNMTC."

The probability argument for raising the threshold to three relatives.

PMID:33025555 REFUTE Human Clinical

"more than 90% of familial cancers were in families with two affected members"

The counterargument - a three-relative rule would exclude the great majority of familial clusters, i.e. most of the low-penetrance disease the polygenic model predicts.

PMID:28657510 SUPPORT Human Clinical

"Thyroid cancer was detected by screening in 4.6% (2/43) of at-risk individuals from families with two members affected, and in 22.7% (15/66) of at-risk members from families with three or more patients affected (p = 0.01)."

Empirical screening-yield gradient supporting stratification by pedigree size.

+ 1 more reference

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Pathophysiology

6

Inherited Non-Syndromic Susceptibility in Thyroid Follicular Cells

The upstream lesion in non-syndromic FNMTC is a constitutional (germline) susceptibility state in the thyroid follicular cell lineage, carried by a family-specific combination of common risk alleles and rare candidate variants rather than by one recurrent high-penetrance driver. Reported contributors include common risk variants near FOXE1 (9q22.33) and NKX2-1 (14q13.3), rare segregating variants in SRGAP1, NKX2-1, FOXE1, SRRM2 and DUOX2, and susceptibility intervals mapped by linkage (TCO/19p13.2, fPTC-PRN/1q21, NMTC1/2q21, MNG1/14q32, FTEN/8p23.1-p22, 6q22, 8q24). Because each family tends to carry its own candidate lesion, this node is defined by the shared consequence - an inherited increase in follicular-cell cancer risk - rather than by a shared gene.

Germline telomere-length dysregulation as an FNMTC predisposition mechanism ⚠ HABP2 p.G534E as an FNMTC susceptibility allele

thyroid follicular cell CL:0002258

FOXE1 hgnc:3806 NKX2-1 hgnc:11825 SRGAP1 hgnc:17382 SRRM2 hgnc:16639

thyroid gland UBERON:0002046

Downstream

Perturbed Thyroid Transcription Factor and Growth-Regulatory Signaling Rare segregating variants in thyroid developmental transcription factors and growth regulators act directly in the follicular cell.

Telomere-Telomerase Imbalance and Chromosome Fragility Familial cases show a constitutional telomere-telomerase imbalance whose causal genes are not identified, so the link is indirect.

HABP2 G534E Loss of Tumor-Suppressor Function Contested branch - proposed as the germline lesion in one kindred but not replicated. Modelled only under the DEPRECATED habp2_g534e_susceptibility hypothesis group.

Show evidence (6 references)

PMID:27807061 SUPPORT Human Clinical

"The causal genes located at the other 7 FNMTC-associated chromosomal loci (TCO (19q13.2), fPTC/ PRN (1q21), FTEN (8p23.1-p22), NMTC1 (2q21), MNG1 (14q32), 6q22, 8q24) have yet to be identified."

Enumerates the classic FNMTC linkage loci and establishes that their causal genes remain unidentified.

PMID:35255942 SUPPORT Human Clinical

"Although syndromic NMTC has well-known genetic risk factors, the gene(s) responsible for the vast majority of non-syndromic FNMTC cases are yet to be identified."

Establishes that the upstream germline lesion for most non-syndromic families is not attributable to a known gene.

PMID:38571492 SUPPORT Human Clinical

"But FNMTC exhibits strong genetic heterogeneity, with each family having its own pathogenic genes."

Supports modeling the trigger as a family-specific susceptibility state rather than one shared gene.

+ 3 more references

Perturbed Thyroid Transcription Factor and Growth-Regulatory Signaling

Functionally characterized FNMTC candidate variants converge on loss of normal restraint over follicular-cell proliferation and differentiation. The germline NKX2-1/TITF-1 A339V variant increases proliferation and thyrotropin-independent growth while impairing transcription of the thyroid-differentiation genes Tg, TSH-R and Pax-8; a germline FOXE1 p.A248G variant promotes proliferation and migration; SRGAP1 variants abolish the protein's ability to inactivate CDC42, a Rho-family GTPase controlling cytoskeletal and growth signaling; and an SRRM2 splicing-factor variant shifts alternative splicing of downstream targets. Individually these are low-penetrance or family-specific effects, but they share the outcome of a follicular cell that is more permissive to transformation.

thyroid follicular cell CL:0002258

NKX2-1 hgnc:11825 FOXE1 hgnc:3806 SRGAP1 hgnc:17382

cell population proliferation GO:0008283 ↑ INCREASED Ras protein signal transduction GO:0007265 ↑ INCREASED

Downstream

Acquisition of Somatic MAPK-Activating Driver Alterations A proliferation-permissive, less-differentiated follicular cell is more likely to fix and expand a somatic MAPK-activating driver.

Show evidence (4 references)

PMID:19176457 SUPPORT In Vitro

"Overexpression of A339V TTF-1 in PCCL3 cells, as compared with overexpression of WT TTF-1, was associated with increased cell proliferation including thyrotropin-independent growth"

Functional assay in normal rat thyroid cells shows the germline TTF-1 variant increases proliferation and confers TSH independence.

PMID:23539728 SUPPORT In Vitro

"Biochemical assays demonstrated that the ability to inactivate CDC42, a key function of SRGAP1, was severely impaired by the Q149H and R617C variants."

Establishes the molecular consequence of segregating SRGAP1 variants as loss of CDC42 inactivation.

PMID:25381600 SUPPORT In Vitro

"we observed that the p.A248G variant promoted cell proliferation and migration, suggesting that it may be involved in thyroid tumorigenesis"

Functional evidence that a segregating germline FOXE1 variant increases follicular-cell proliferation and migration.

+ 1 more reference

Telomere-Telomerase Imbalance and Chromosome Fragility

Patients with familial papillary thyroid carcinoma show a constitutional imbalance of the telomere-telomerase complex in peripheral blood - shorter relative telomere length than sporadic cases, unaffected siblings and healthy controls, together with hTERT/TERT gene amplification and increased telomerase activity. The same familial cohorts show a significant excess of spontaneous telomeric associations and telomeric fusions, i.e. measurable constitutional chromosome instability. This arm is a candidate constitutional mechanism of predisposition, distinct from the tumor-intrinsic telomere-maintenance reactivation (TERT promoter mutation) seen in advanced sporadic thyroid cancer.

Germline telomere-length dysregulation as an FNMTC predisposition mechanism

TERT hgnc:11730

telomere maintenance GO:0000723 ⚠ ABNORMAL telomere maintenance via telomerase GO:0007004 ↑ INCREASED

Downstream

Acquisition of Somatic MAPK-Activating Driver Alterations Constitutional telomeric instability plausibly raises the rate at which follicular cells acquire and fix oncogenic somatic alterations.

Show evidence (3 references)

PMID:18664542 SUPPORT Human Clinical

"Our study demonstrates that patients with FPTC display an imbalance of the telomere-telomerase complex in the peripheral blood, characterized by short telomeres, hTERT gene amplification, and expression."

Direct human evidence for the constitutional telomere-telomerase imbalance modeled by this node.

PMID:18664542 PARTIAL Human Clinical

"These features may be implicated in the inherited predisposition to develop FPTC."

The authors themselves frame the causal role in predisposition as a possibility, so the predisposition claim is only partially supported.

PMID:22539583 SUPPORT Human Clinical

"We demonstrate that fPTC patients have a significant increase in spontaneous telomeric associations and telomeric fusions compared with healthy subjects and sporadic cases in the frame of an otherwise common spontaneous chromosome fragility pattern."

Supports measurable constitutional chromosomal instability in familial cases, the basis for the genome_instability_mutation conformance.

Acquisition of Somatic MAPK-Activating Driver Alterations

Familial and sporadic non-medullary thyroid carcinoma share the same morphology and the same somatic driver landscape - BRAF V600E, RAS-family mutations, RET/PTC and NTRK fusions - so the germline susceptibility layer does not create a distinct tumor genotype; it raises the probability that a follicular cell acquires one of the ordinary MAPK-activating drivers, and it does so in many cells at once, which is the mechanistic basis for the excess multifocality and bilaterality of familial tumors. Somatic BRAF V600E has been documented in the tumors of family members carrying a segregating germline FOXE1 variant, directly illustrating the germline-plus-somatic two-layer model. The somatic driver biology itself is curated in the sporadic entries (Papillary Thyroid Carcinoma, Thyroid Follicular Carcinoma, BRAF Mutant Thyroid Cancer, RET Fusion Thyroid Cancer) and is not duplicated here.

thyroid follicular cell CL:0002258

MAPK cascade GO:0000165 ↑ INCREASED phosphatidylinositol 3-kinase/protein kinase B signal transduction GO:0043491 ↑ INCREASED

Downstream

Multifocal Follicular Cell Transformation Constitutive mitogenic signaling drives clonal expansion and transformation.

Show evidence (4 references)

PMID:35295987 SUPPORT Human Clinical

"Given that non-syndromic familial non-medullary carcinoma and sporadic non-medullary thyroid carcinoma share the same morphology and somatic mutations, the same targeted therapies could be used at present"

Establishes that the somatic driver layer of familial tumors is the same as that of sporadic tumors.

PMID:25381600 SUPPORT Human Clinical

"Additionally, somatic p.V600E BRAF mutations were also detected in the thyroid tumors of two members of the family carrying the p.A248G variant."

Worked example of the germline-susceptibility-plus-somatic-MAPK-driver two-layer model within a single FNMTC kindred.

PMID:37438605 SUPPORT Human Clinical

"Essentially, the main oncoproteins in thyroid cancer activate nodes in the receptor tyrosine kinase-RAS-BRAF pathway, which constitutively induces MAPK signalling to varying degrees consistent with their specific biochemical mechanisms of action."

Authoritative review establishing that the follicular-cell thyroid cancer drivers converge on constitutive MAPK signalling - the mechanistic anchor for this node's GO:0000165 annotation.

+ 1 more reference

Multifocal Follicular Cell Transformation

Transformation occurs against a field of inherited susceptibility, so it is characteristically multicentric and bilateral, frequently accompanied by benign follicular adenoma and multinodular goiter in the same gland and in unaffected relatives. Tumors then follow the ordinary differentiated thyroid-cancer natural history - intrathyroidal growth, extrathyroidal extension, cervical nodal spread and, less often, distant metastasis - with familial series showing a more aggressive presentation at diagnosis but not a worse outcome after appropriate treatment.

Genetic anticipation in FNMTC across generations

thyroid follicular cell CL:0002258

thyroid gland UBERON:0002046

Downstream

Papillary Thyroid Carcinoma The dominant malignant histology in familial kindreds.

Follicular Thyroid Carcinoma A minority of familial tumors are follicular-patterned carcinoma.

Multifocal and Bilateral Thyroid Carcinoma Field predisposition produces multicentric and bilateral disease.

Benign Thyroid Nodules and Multinodular Goiter Benign follicular neoplasia accompanies the malignant field.

Cervical Lymphadenopathy Regional nodal spread from the primary tumor.

Extrathyroidal Extension Locally invasive growth beyond the thyroid capsule.

Pulmonary Metastasis Distant haematogenous spread in a minority of familial cases.

Earlier Age at Onset in Successive Generations Observed clinical anticipation, at least partly confounded by ascertainment and surveillance intensity.

Show evidence (2 references)

PMID:35295987 SUPPORT Human Clinical

"Most cases are papillary thyroid carcinoma (classic and follicular variant), usually accompanied by benign thyroid nodules (follicular thyroid adenoma and/or multinodular goiter)."

Supports the multifocal thyroid-neoplasia field, malignant and benign, that characterizes the transformed gland in FNMTC.

PMID:33488516 SUPPORT Human Clinical

"We found that familial tumors had a statistically significant more aggressive presentation at diagnosis, though not resulting in a worst outcome."

Supports the more aggressive presentation with preserved outcome that characterizes the clinical consequence node.

HABP2 G534E Loss of Tumor-Suppressor Function

CONTESTED - retained as a modelled but refuted branch, not part of the canonical FNMTC mechanism. In 2015 a germline HABP2 c.1601G>A (p.G534E) variant was reported to segregate with disease in all seven affected members of one FNMTC kindred, to be present in 4.7% of 423 TCGA papillary thyroid cancers, and to behave as a dominant-negative loss of a tumor-suppressive function in colony-formation, foci and migration assays performed in NIH-3T3 fibroblasts rather than in thyroid cells. One independent kindred series supported a susceptibility role in a subgroup. Multiple independent replication studies then contradicted causality on three separate grounds: failure of cosegregation within carrier families, population carrier frequencies of 7.6-9.3% that are incompatible with a highly penetrant dominant allele, and absence of HABP2 expression in thyroid tissue. This node exists so that the DEPRECATED habp2_g534e_susceptibility hypothesis group is wired to real causal edges and the controversy stays auditable rather than being silently deleted.

⚠ HABP2 p.G534E as an FNMTC susceptibility allele

thyroid follicular cell CL:0002258

HABP2 hgnc:4798

Downstream

Multifocal Follicular Cell Transformation Proposed but unreplicated route from HABP2 loss of function to malignant transformation of the follicular epithelium.

Show evidence (8 references)

PMID:26222560 SUPPORT In Vitro

"Since we did not find alterations in the other HABP2 allele in the tumor tissue and our functional studies suggested that HABP2 has a tumor-suppressive effect, we cotransfected equal amounts of the wild-type and G534E mutant constructs into NIH-3T3 cells."

The original functional claim - a dominant-negative effect on a tumor-suppressive HABP2 function, demonstrated in fibroblasts rather than in thyroid cells.

PMID:26222560 SUPPORT Human Clinical

"Finally, analysis of TCGA data in 423 patients with papillary thyroid cancer showed that 4.7% carried the HABP2 G534E variant, as compared with 0.7% of persons with unknown disease status in multiethnic population databases (P<0.001)."

The case-control frequency argument offered in the original report.

PMID:26832773 SUPPORT Human Clinical

"These results are consistent with HABP2 G534E being a susceptibility gene in a subgroup of FNMTC, providing important diagnostic implications for this hereditary thyroid cancer."

The principal independent report favouring a susceptibility role, so both sides of the controversy are represented rather than only the refutations.

+ 5 more references

✶

Histopathology

2

Multifocality FREQUENT

More than one discrete tumour focus within the thyroid, frequently bilateral. Reported at higher frequency in familial than in matched sporadic disease in independent meta-analyses and is the histopathologic correlate of the field-predisposition model.

Show evidence (1 reference)

PMID:25637073 SUPPORT Human Clinical

"higher risk of multifocal (OR=1.50, 95% CI: 1.32 to 1.71), bilateral (OR=1.29, 95% CI: 1.00 to 1.66)"

Pooled odds ratios for multifocality and bilaterality across 12 studies.

Oxyphilic (Hurthle) Cell Change

Oncocytic / oxyphilic cytoplasmic change affecting both benign and malignant thyroid tumours within the same kindred. Diagnostic of the TCO (19p13.2) subtype rather than of FNMTC generally.

Show evidence (1 reference)

PMID:9837827 SUPPORT Human Clinical

"Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC."

Defines the oxyphilic histopathologic signature of the TCO subtype.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

●

Phenotypes

13

Cardiovascular 1

Cervical Lymphadenopathy Cervical lymphadenopathy HP:0025289

Show evidence (1 reference)

PMID:18832444 SUPPORT Human Clinical

"their tumors were more frequently multifocal (P=0.003) and bilateral (P=0.01), had higher rate of lymph node metastases at surgery (P=0.02) and worse outcome (P=0.04) when compared with the first generation"

Documents cervical nodal metastasis in familial kindreds and its generational gradient.

Endocrine 1

Multifocal and Bilateral Thyroid Carcinoma FREQUENT Thyroid carcinoma HP:0002890

Show evidence (3 references)

PMID:26191611 SUPPORT Human Clinical

"Compared with sporadic PTC, patients with FPTC were more likely to present tumour multicentricity, bilateral growth and a concomitant nodular goitre"

Matched case-control study of 372 familial versus 372 sporadic papillary carcinomas supports excess multicentricity and bilaterality.

PMID:18832444 SUPPORT Human Clinical

"Significant difference between sporadic PTC and FNMTC patients included more frequent tumor multifocality (P=0.001) and worse final outcome in FNMTC patients (P=0.001)."

Independent cohort comparison supporting excess multifocality in familial versus sporadic disease.

PMID:11438887 SUPPORT Human Clinical

"The familial form of nonmedullary thyroid carcinoma (NMTC) is a complex genetic disorder characterized by multifocal neoplasia and a higher degree of aggressiveness than its sporadic counterpart."

Independently characterizes multifocal neoplasia as a defining clinical feature of familial NMTC.

Neoplasm 1

Pulmonary Metastasis Neoplasm of the lung HP:0100526

No `frequency:` band is asserted. The available quantitative source (PMID:40908394) reports a relative measure - pooled odds ratios versus sporadic disease - not an absolute rate, and no cached abstract gives a per-patient distant-metastasis frequency in familial cohorts. A band was previously asserted here on a methods sentence that carried no frequency information; that is corrected rather than re-sourced.

Show evidence (2 references)

PMID:40908394 SUPPORT Human Clinical

"distant metastasis (OR: 2.43 and 3.93)"

Pooled odds ratios for distant metastasis in two-relative and three-or-more-relative familial disease versus sporadic non-medullary thyroid carcinoma - the largest familial effect size in this entry's evidence base, and a relative rather than absolute measure, which is why no frequency band is derived from it.

PMID:25637073 PARTIAL Human Clinical

"FNMTC patients had an increased rate of recurrence (OR=1.72, 95% CI: 1.34 to 2.20) and decreased disease-free survival (DFS) (HR=1.83, 95% CI: 1.34 to 2.52) in comparison with SNMTC patients."

Supports the adverse-outcome dimension of which distant metastasis is the most severe component; PARTIAL because the pooled estimate is for recurrence and disease-free survival rather than for distant metastasis specifically.

Other 10

Non-Medullary Thyroid Carcinoma OBLIGATE Non-medullary thyroid carcinoma HP:0040198

Show evidence (2 references)

PMID:26222560 SUPPORT Human Clinical

"Thyroid cancers of follicular-cell origin account for more than 95% of all cases of thyroid cancer, with the remaining cancers originating from parafollicular cells (medullary thyroid cancer)."

Defines the follicular-cell versus parafollicular-cell boundary that makes "non-medullary" the operative disease-defining phenotype.

PMID:33488516 SUPPORT Human Clinical

"The term familial non-medullary thyroid cancers (FNMTCs) is used to indicate thyroid tumors, arising from follicular cells, which are observed in two or more first-degree relatives in the absence of predisposing environmental factors."

Confirms follicular-cell origin as definitional, supporting the OBLIGATE frequency band.

Papillary Thyroid Carcinoma VERY_FREQUENT Papillary thyroid carcinoma HP:0002895

Show evidence (2 references)

PMID:35295987 SUPPORT Human Clinical

"Most cases are papillary thyroid carcinoma (classic and follicular variant), usually accompanied by benign thyroid nodules (follicular thyroid adenoma and/or multinodular goiter)."

Supports papillary carcinoma as the predominant (very frequent) histology of non-syndromic FNMTC.

PMID:33025555 SUPPORT Human Clinical

"Familial non-medullary thyroid carcinoma (FNMTC), mainly of papillary histotype (FPTC), is defined by the presence of the disease in two or more first-degree relatives in the absence of other known familial syndromes."

Confirms the papillary histotype predominance that justifies the VERY_FREQUENT band.

Follicular Thyroid Carcinoma OCCASIONAL Follicular thyroid carcinoma HP:0006731

Show evidence (1 reference)

PMID:9837827 SUPPORT Human Clinical

"Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC."

Documents non-papillary (oxyphilic follicular) malignant histology within an FNMTC kindred.

Benign Thyroid Nodules and Multinodular Goiter FREQUENT Multinodular goiter HP:0005987

Show evidence (2 references)

PMID:35295987 SUPPORT Human Clinical

"usually accompanied by benign thyroid nodules (follicular thyroid adenoma and/or multinodular goiter)"

States that benign nodular disease usually accompanies the familial carcinoma.

PMID:9837827 SUPPORT Human Clinical

"Cases of benign thyroid disease are often found in FNMTC kindreds."

Independently supports the enrichment of benign thyroid disease within FNMTC families.

Thyroid Nodule Thyroid nodule HP:0025388

Show evidence (1 reference)

PMID:28657510 SUPPORT Human Clinical

"A prospective cohort study was performed with yearly screening using neck ultrasound and fine-needle aspiration biopsy of thyroid nodule(s) >0.5 cm in at-risk individuals whose relatives were diagnosed with familial non-medullary thyroid cancer (FNMTC)."

Documents the thyroid nodule as the screening target and index lesion in at-risk FNMTC relatives, and the size threshold applied to it.

Extrathyroidal Extension Neoplasm of the thyroid gland HP:0100031

HPO has no term for extrathyroidal extension specifically, so the descriptor is bound to the nearest available thyroid-neoplasm parent and the invasive behaviour is carried by preferred_term and description.

Show evidence (1 reference)

PMID:33488516 PARTIAL Human Clinical

"We found that familial tumors had a statistically significant more aggressive presentation at diagnosis, though not resulting in a worst outcome."

Supports the aggressive local presentation of which extrathyroidal extension is a component; the abstract does not itself break out the extension rate, so support is partial.

Earlier Age at Onset in Successive Generations

Deliberately left without a `phenotype_term`. HPO's only anticipation concept, HP:0003743 "Genetic anticipation", is NOT a phenotypic abnormality: `runoak -i sqlite:obo:hp ancestors -p i HP:0003743` returns only HP:0000001, HP:0000005 (Mode of inheritance) and HP:0034335 (Inheritance qualifier), so it is not reachable from HP:0000118 and cannot validate against the PhenotypeTerm dynamic enum, whose source nodes are HP:0000118 and MONDO:0000001. Its definition ("A type of autosomal dominant inheritance involving a gene that exhibits anticipation...") also asserts an inheritance mechanism, which would over-commit this entry to the ALTERNATIVE anticipation hypothesis rather than merely recording the observation. The previous binding to HP:0100031 "Neoplasm of the thyroid gland" was a genuine term-claim mismatch and has been removed rather than replaced. An NTR for a phenotypic-abnormality term expressing "earlier age at onset in successive generations" would be the clean resolution.

Show evidence (2 references)

PMID:18832444 SUPPORT Human Clinical

"Among 47 FNMTC with parent-child relationship, we found an earlier age at disease presentation (P<0.0001), diagnosis (P<0.0001), and disease onset (P=0.04) in the second generation when compared with the first generation."

Primary quantitative evidence for earlier onset in the second generation.

PMID:26191611 SUPPORT Human Clinical

"The presence of familial history in PTC indicates an increase in biological aggressiveness, and patients in the second generation may exhibit the 'genetic anticipation' phenomenon."

Independent matched case-control replication of the anticipation observation.

Hurthle Cell Thyroid Adenoma Hurthle cell thyroid adenoma HP:0006781

Show evidence (1 reference)

PMID:9837827 SUPPORT Human Clinical

"Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC."

Establishes oxyphilic change in the benign as well as the malignant tumours of the TCO kindred, which is what binds this descriptor to the adenoma rather than the carcinoma term.

Papillary Renal Neoplasia Papillary renal cell carcinoma HP:0006766

Show evidence (1 reference)

PMID:10843148 SUPPORT Human Clinical

"In addition to the known association of fPTC with nodular thyroid disease, we observed the otherwise rare entity of papillary renal neoplasia (PRN) in two kindred members, one affected with PTC and the other an obligate carrier."

Documents papillary renal neoplasia in the index fPTC/PRN kindred, including in an obligate carrier.

Hashimoto Thyroiditis Hashimoto thyroiditis HP:0000872

Show evidence (1 reference)

PMID:26191611 SUPPORT Human Clinical

"The patients with FPTC in the second generation showed an earlier age of onset, more frequent Hashimoto's thyroiditis and a higher recurrence rate than the first generation"

Reports excess Hashimoto thyroiditis in second-generation familial papillary thyroid carcinoma.

🧬

Genetic Associations

16

FOXE1 (Susceptibility - best-replicated locus (9q22.33), common risk allele plus rare segregating variants)

Gene: FOXE1 hgnc:3806 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (3 references)

PMID:19198613 SUPPORT Human Clinical

"Overall, the strongest association signals were observed for rs965513 on 9q22.33 (OR = 1.75; P = 1.7 x 10(-27)) and rs944289 on 14q13.3 (OR = 1.37; P = 2.0 x 10(-9))."

Genome-wide association evidence for the FOXE1-proximal 9q22.33 common risk allele, the most consistently replicated thyroid cancer susceptibility signal.

PMID:19198613 SUPPORT Human Clinical

"The gene nearest to the 9q22.33 locus is FOXE1 (TTF2) and NKX2-1 (TTF1) is among the genes located at the 14q13.3 locus. Both variants contribute to an increased risk of both papillary and follicular thyroid cancer."

Assigns the 9q22.33 and 14q13.3 signals to FOXE1 and NKX2-1 respectively, for both papillary and follicular histology.

PMID:25381600 SUPPORT Human Clinical

"This study represents the first evidence of involvement of a germline FOXE1 rare variant in FNMTC etiology and suggests that mutations in MAPK pathway-related genes may contribute to tumor development in these familial cases."

Extends FOXE1 from a common-variant risk locus to a rare germline variant segregating in an FNMTC family.

NKX2-1 (TITF-1) (Susceptibility - 14q13.3 common risk allele plus the germline A339V variant in MNG/PTC families)

Gene: NKX2-1 hgnc:11825 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (2 references)

PMID:19176457 SUPPORT Human Clinical

"A missense mutation (1016C>T) was identified in TITF-1/NKX2.1 that led to a mutant TTF-1 protein (A339V) in four of the 20 MNG/PTC patients (20%)."

Identifies the recurrent germline NKX2-1 variant in patients with multinodular goiter and papillary carcinoma.

PMID:19176457 SUPPORT Human Clinical

"Notably, this germline mutation was dominantly inherited in two families, with some members bearing the mutation affected with MNG, associated with either PTC or colon cancer."

Demonstrates dominant familial transmission of the A339V allele.

SRGAP1 (Susceptibility - low-penetrance / possible modifier gene at 12q14)

Gene: SRGAP1 hgnc:17382 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (3 references)

PMID:23539728 SUPPORT Human Clinical

"Linkage analysis and association studies identified the Slit-Robo Rho GTPase activating protein 1 gene (SRGAP1) in the linkage peak as a candidate gene."

Genome-wide linkage in 38 families plus association testing nominated SRGAP1.

PMID:23539728 PARTIAL Human Clinical

"Our findings suggest that SRGAP1 is a candidate gene in PTC susceptibility. SRGAP1 is likely a low-penetrant gene, possibly of a modifier type."

The authors themselves classify SRGAP1 as a candidate low-penetrance/modifier gene rather than an established cause.

PMID:27530615 REFUTE Human Clinical

"From whole exome data, pathogenic mutations were not identified in HABP2, SRGAP1, NKX2-1, SRRM2 or FOXE1."

Exome sequencing of 59 participants from 20 independent Australian FNMTC kindreds found no pathogenic SRGAP1 variants, arguing against a general role.

SRRM2 (Susceptibility - single-family splicing-factor candidate, not replicated in other kindreds)

Gene: SRRM2 hgnc:16639 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (1 reference)

PMID:26135620 PARTIAL Human Clinical

"This heterozygous variant, c.1037C > T (Ser346Phe or S346F; rs149019598) cosegregated with PTC in the family. It was not found in 138 other PTC families."

Cosegregation in one six-case family supports the variant, but its absence from 138 further PTC families shows it does not generalize, so support for a disease-wide role is partial.

HABP2 (Disputed - the p.G534E variant was proposed as a dominant susceptibility allele but failed replication and is common in the general population)

Gene: HABP2 hgnc:4798 relationship_type: DISPUTED variant_origin: GERMLINE

Show evidence (10 references)

PMID:26222560 SUPPORT Human Clinical

"Here, we report a germline variant of HABP2 in seven affected members of a kindred with familial nonmedullary thyroid cancer and in 4.7% of 423 patients with thyroid cancer."

The original report proposing germline HABP2 as an FNMTC susceptibility gene.

PMID:26222560 SUPPORT In Vitro

"Functional studies showed that HABP2 has a tumor-suppressive effect, whereas the G534E variant results in loss of function."

The functional argument offered in support of the original claim.

PMID:27530615 REFUTE Human Clinical

"Heterozygosity for the G534E variant in HABP2 was found in 1 of 37 probands (2.7 %), but did not cosegregate with disease in this kindred, being absent in the proband's affected sister."

Direct refutation - the variant failed to cosegregate with disease in the one kindred in which it was found.

+ 7 more references

NID1 (Candidate only - single-family whole-exome finding awaiting replication)

Gene: NID1 hgnc:7821 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (1 reference)

PMID:34941562 PARTIAL Human Clinical

"The missense variant p.Ile657Met in the NID1 gene was the only variant that co-segregated with the disease, while absent in unaffected family members and controls."

The cosegregation finding in the single index family; PARTIAL because no independent replication exists and the authors explicitly call for it.

MAP2K5 (Disputed - reported candidate not confirmed in independent FNMTC series)

Gene: MAP2K5 hgnc:6845 relationship_type: DISPUTED variant_origin: GERMLINE

Show evidence (2 references)

PMID:38571492 SUPPORT Human Clinical

"Subsequent research employed more advanced techniques such as Genome-wide Association Study and Whole Exome Sequencing, leading to the discovery of genes such as IMMP2L, GALNTL4, WDR11-AS1, DUOX2, NOP53, MAP2K5, and others."

Records MAP2K5 among the sequencing-era candidate genes reported for non-syndromic FNMTC.

PMID:33488516 REFUTE Human Clinical

"Our families are negative for variants reported as likely causative, namely those lying in the HABP2, MAP2K5 and DUOX2 genes."

An independent series of 33 FNMTC families carried no reported MAP2K5 variant, arguing against a general causal role.

DUOX2 (Disputed - single-family candidate variant absent from an independent validation series)

Gene: DUOX2 hgnc:13273 relationship_type: DISPUTED variant_origin: GERMLINE

Show evidence (1 reference)

PMID:33488516 REFUTE Human Clinical

"Unfortunately, the DUOX2 p.Y1203H variant was not found in either the 74 affected or the 12 not affected family members of our series."

Explicit failed validation of the DUOX2 candidate variant in 86 members of 33 independent FNMTC families.

APC (Causative for the syndromic form - familial adenomatous polyposis / Gardner syndrome with cribriform-morular thyroid carcinoma)

Gene: APC hgnc:583 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (4 references)

PMID:27807061 SUPPORT Human Clinical

"Out of all FNMTC cases, only 5% in the syndromic form has well-studied driver germline mutations. These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Establishes familial adenomatous polyposis / Gardner syndrome as one of the well-characterized syndromic causes to be excluded.

PMID:24093640 SUPPORT Human Clinical

"Lifetime risk of thyroid cancer associated with FAP has been reported as 1-2%. The mean age at diagnosis of thyroid carcinoma in FAP has been reported at 28 years."

Quantifies the magnitude and age profile of APC-associated thyroid cancer risk, which is what makes recognizing FAP actionable in a young FNMTC-like proband.

PMID:24093640 SUPPORT Human Clinical

"There is increased risk for thyroid cancer in individuals with APC mutations at the 5' end (proximal to codon 528) along with the established high risk group harboring mutation at codon 1061."

Gives the APC genotype-to-thyroid-phenotype correlation within FAP.

+ 1 more reference

PTEN (Causative for the syndromic form - Cowden syndrome / PTEN hamartoma tumor syndrome)

Gene: PTEN hgnc:9588 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (3 references)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Establishes Cowden syndrome as a syndromic cause of familial non-medullary thyroid carcinoma.

PMID:22252256 SUPPORT Human Clinical

"thyroid (51.1, 38.1-67.1)"

Standardised incidence ratio of 51.1 (95% CI 38.1-67.1) for thyroid cancer in a prospective cohort of 3,399 individuals of whom 368 carried deleterious germline PTEN mutations - among the highest component-cancer risks in PHTS and the quantitative reason PTEN testing is actionable.

PMID:22252256 SUPPORT Human Clinical

"A series of 3,399 individuals meeting relaxed International Cowden Consortium PHTS criteria were prospectively recruited; 368 individuals were found to have deleterious germline PTEN mutations."

Establishes the prospective PHTS cohort from which the thyroid SIR is derived.

PRKAR1A (Causative for the syndromic form - Carney complex type 1)

Gene: PRKAR1A hgnc:9388 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (3 references)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Establishes Carney complex type 1 as a syndromic cause to be excluded before diagnosing non-syndromic FNMTC.

PMID:16756677 SUPPORT Human Clinical

"The most common endocrine gland manifestations are acromegaly, thyroid and testicular tumors, and adrenocorticotropic hormone (ACTH)-independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD)."

Places thyroid tumours among the core endocrine manifestations of Carney complex, which is what makes the syndrome relevant to an FNMTC-like pedigree.

PMID:16756677 SUPPORT Human Clinical

"Heterozygous inactivating mutations of PRKAR1A were reported initially in 45 to 65% of CNC index cases, and may be present in about 80% of the CNC families presenting mainly with Cushing's syndrome."

Gives the PRKAR1A mutation detection rate, i.e. the expected yield of targeted testing when Carney complex is suspected.

WRN (Causative for the syndromic form - Werner syndrome)

Gene: WRN hgnc:12791 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (3 references)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Establishes Werner syndrome as a syndromic cause to be excluded.

PMID:23573208 SUPPORT Human Clinical

"Werner syndrome (WS) is an autosomal recessive genetic instability and progeroid ('premature aging') syndrome which is associated with an elevated risk of cancer."

Establishes the autosomal recessive, genomic-instability mechanism - WRN is the only recessive member of the syndromic set, which matters when interpreting a pedigree that lacks vertical transmission.

PMID:23573208 SUPPORT Human Clinical

"Cancer risk defined by SIRs was significantly elevated in Japan-resident WS patients for the six most frequent neoplasms except leukemia, ranging from 53.5-fold for melanoma of the skin (95% CI: 24.5, 101.6) to 8.9 (95% CI: 4.9, 15.0) for thyroid neoplasms."

Quantifies the thyroid-neoplasm standardised incidence ratio (8.9) in Werner syndrome.

DICER1 (Causative for the syndromic form - DICER1 tumor predisposition syndrome)

Gene: DICER1 hgnc:17098 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (3 references)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Establishes DICER1 syndrome as a syndromic cause to be excluded.

PMID:24761742 SUPPORT Human Clinical

"The most common features are lung cysts and thyroid nodules."

GeneReviews statement placing thyroid nodules among the two commonest DICER1 features - the reason a childhood-onset nodular thyroid pedigree should prompt DICER1 testing rather than an FNMTC label.

PMID:24761742 SUPPORT Human Clinical

"DICER1-related neoplasms include pleuropulmonary blastoma (PPB), Sertoli-Leydig cell tumor (SLCT), including gynandroblastoma, pediatric cystic nephroma (CN), and differentiated thyroid carcinoma."

Confirms differentiated thyroid carcinoma as part of the DICER1 tumour spectrum.

POT1 (Germline pathogenic POT1 variants produce ultra-long telomeres and, together with TINF2 and ACD, define a recently delineated long-telomere syndromic papillary thyroid cancer subtype found in 4.5% of familial and 1.5% of unselected cases. Note the direction of effect - this is telomere LENGTHENING, the mirror image of the telomere-shortening/fragility model.)

Gene: POT1 hgnc:17284 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (2 references)

PMID:38688277 SUPPORT Human Clinical

"Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD."

Identifies POT1 among the three shelterin predisposition genes.

PMID:38688277 SUPPORT Human Clinical

"They were found in 4.5% and 1.5% of familial and unselected cases, respectively."

Quantifies the shelterin contribution to familial papillary thyroid cancer.

TINF2 (Germline pathogenic TINF2 variants contribute to the long-telomere papillary thyroid cancer subtype.)

Gene: TINF2 hgnc:11824 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (1 reference)

PMID:38688277 SUPPORT Human Clinical

"Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD."

Identifies TINF2 among the three shelterin predisposition genes.

ACD (Germline pathogenic ACD (TPP1) variants contribute to the long-telomere papillary thyroid cancer subtype.)

Gene: ACD hgnc:25070 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (1 reference)

PMID:38688277 SUPPORT Human Clinical

"Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD."

Identifies ACD among the three shelterin predisposition genes.

💊

Medical Actions

7

Thyroidectomy

Action: Thyroidectomy NCIT:C51648

Surgery is the definitive treatment and follows standard differentiated thyroid-cancer risk stratification - lobectomy or total thyroidectomy according to tumor size, multifocality and bilaterality, nodal disease and patient preference. Because familial tumors are more often multicentric and bilateral, total thyroidectomy is used frequently in referral series, but current guidance does not mandate a more aggressive operation on the basis of family history alone.

Mechanism Target:

INHIBITS Multifocal Follicular Cell Transformation — Removing both lobes eliminates the multicentric and contralateral disease that field predisposition produces, which is the mechanistic rationale for favouring total over partial thyroidectomy in familial kindreds.

Show evidence (3 references)

PMID:26191611 SUPPORT Human Clinical

"At present, the available data are not sufficient to support a more aggressive approach for FPTC."

Directly supports the statement that family history alone does not justify escalating the initial operation.

PMID:33488516 SUPPORT Human Clinical

"Despite the more aggressive presentation of familial cases, an appropriate treatment leads to an outcome similar to that observed for sporadic cases."

Supports treating FNMTC by standard differentiated thyroid-cancer principles rather than a familial-specific escalation.

PMID:40392709 SUPPORT Human Clinical

"Therefore, the management of FNMTC should align with the standard of care for DTC to avoid overtreatment of FNMTC."

Explicit recommendation against escalating surgery on the basis of familial status alone, and the source of the overtreatment concern.

Thyroid Lobectomy

Action: Thyroid Lobectomy NCIT:C51649

Lobectomy remains appropriate for selected small, unifocal, low-risk familial tumours - notably screen-detected cancers, where hemithyroidectomy was used in 23.5% of screen-detected FNMTC versus 0% of clinically presenting cases. The choice between lobectomy and total thyroidectomy should follow standard differentiated-thyroid-cancer risk stratification rather than family history alone, and is the operative counterweight to the reflex-total-thyroidectomy tendency in familial disease.

Show evidence (2 references)

PMID:28657510 SUPPORT Human Clinical

"less extensive surgery (hemithyroidectomy 23.5% vs. 0%; p = 0.002)"

Quantifies the use of hemithyroidectomy for screen-detected, low-risk familial disease versus clinically presenting disease.

PMID:26191611 SUPPORT Human Clinical

"At present, the available data are not sufficient to support a more aggressive approach for FPTC."

Supports retaining lobectomy as an option - family history alone does not justify mandating the more extensive operation.

Cervical Lymph Node Dissection

Action: Neck Dissection NCIT:C15643

Therapeutic compartment-oriented neck dissection is performed for proven nodal metastasis, following standard differentiated thyroid-cancer indications. Familial series report higher nodal metastasis rates than sporadic disease, but screen-detected familial cancers have a substantially lower central-node metastasis rate (17.6% versus 51.1%), so nodal management should be driven by imaging and cytology findings rather than by familial status.

Mechanism Target:

INHIBITS Multifocal Follicular Cell Transformation — Compartment-oriented dissection removes the regional nodal disease that the transformed, frequently multicentric gland has seeded.

Show evidence (2 references)

PMID:28657510 SUPPORT Human Clinical

"a lower rate of central neck lymph node metastases (17.6% vs. 51.1%; p = 0.02)"

Quantifies central nodal involvement in screen-detected versus clinically detected familial disease - the reason nodal surgery is findings-driven rather than familial-status-driven.

PMID:18832444 PARTIAL Human Clinical

"had higher rate of lymph node metastases at surgery (P=0.02) and worse outcome (P=0.04) when compared with the first generation"

Establishes the burden of surgically confirmed nodal metastasis that neck dissection addresses; the abstract does not itself evaluate the operation, so support for the intervention is indirect.

Radioactive Iodine Therapy

Action: Radioactive Iodine Therapy NCIT:C157968

Adjuvant radioiodine (I-131) is selected after surgery according to recurrence risk and radioiodine avidity, exactly as for sporadic differentiated thyroid cancer. Family history is not itself an indication.

Show evidence (3 references)

PMID:35295987 PARTIAL Human Clinical

"Given that non-syndromic familial non-medullary carcinoma and sporadic non-medullary thyroid carcinoma share the same morphology and somatic mutations, the same targeted therapies could be used at present"

Supports applying standard sporadic differentiated thyroid-cancer treatment to familial disease; the quoted sentence concerns targeted therapy specifically, so support for the radioiodine indication is partial.

PMID:28657510 SUPPORT Human Clinical

"a lower rate of radioactive iodine therapy (23.5% vs. 79%; p < 0.001) compared to those affected at enrollment."

Shows that radioiodine use tracks disease stage at detection rather than familial status - screen-detected familial cancers needed it far less often than clinically presenting ones.

PMID:40392709 SUPPORT Human Clinical

"There was no difference in radioactive iodine (RAI) therapy dosage between the groups"

Matched-cohort evidence that administered radioiodine activity does not differ by familial status, supporting risk-adapted rather than familial-status-adapted dosing.

Levothyroxine Replacement and TSH Suppression

Action: Pharmacotherapy NCIT:C15986

Agent: levothyroxine NCIT:C62080

Thyroid hormone replacement is mandatory after total thyroidectomy, with risk-adapted TSH suppression as part of standard differentiated thyroid-cancer follow-up.

Show evidence (1 reference)

PMID:33488516 PARTIAL Human Clinical

"The extensive review of the current knowledge on the genetic risk factors for non-syndromic FNMTCs underlies how the management of these tumors remains mainly clinical."

Supports that FNMTC management is standard clinical differentiated thyroid-cancer care, of which post-thyroidectomy levothyroxine is a constituent; the abstract does not name levothyroxine, so support is partial.

Kinase Inhibitor Therapy for Radioiodine-Refractory Disease

Action: targeted therapy Ontology label: Targeted Therapy NCIT:C93352

Agent: selpercatinib NCIT:C134987 dabrafenib CHEBI:75045 lenvatinib CHEBI:85994

Advanced radioiodine-refractory familial tumors are treated with molecularly selected kinase inhibition on the same rules as sporadic differentiated thyroid cancer - RET or NTRK inhibitors for the corresponding fusions, BRAF/MEK-directed therapy for BRAF-altered disease, and multikinase inhibitors otherwise - because the somatic driver landscape is shared.

Mechanism Target:

INHIBITS Acquisition of Somatic MAPK-Activating Driver Alterations — Kinase inhibitors act on the same somatic MAPK/RTK driver layer in familial tumors as in sporadic differentiated thyroid cancer.

Show evidence (1 reference)

PMID:35295987 SUPPORT Human Clinical

"Given that non-syndromic familial non-medullary carcinoma and sporadic non-medullary thyroid carcinoma share the same morphology and somatic mutations, the same targeted therapies could be used at present, if necessary, until more specific targeted treatments become available."

Directly supports applying the sporadic targeted-therapy repertoire to familial tumors on the grounds of shared somatic drivers.

Genetic Counseling and Family Risk Assessment

Action: Genetic Counseling NCIT:C15240

Counseling covers a three-generation pedigree, recognition of syndromic features that would redirect testing to APC, PTEN, PRKAR1A, WRN or DICER1, and an explicit explanation that no validated predictive gene panel exists for isolated non-syndromic kindreds. Current major-society guidance does not recommend routine screening of first-degree relatives of patients with differentiated thyroid cancer, so surveillance decisions are individualized - with a lower threshold in families with three or more affected members, unusually young onset, or aggressive disease.

Show evidence (2 references)

PMID:33025555 SUPPORT Human Clinical

"For this reason, recent guidelines do not recommend screening of family members of patients with diagnosis of differentiated thyroid cancer"

Supports the statement that routine relative screening is not currently guideline-recommended.

PMID:27807061 SUPPORT Human Clinical

"It is important for the clinician to recognize these phenotypes so that genetic counseling and testing can be initiated to enable surveillance for associated malignancies and genetic testing of family members."

Supports phenotype-directed recognition of syndromic forms as the core counseling task.

🔀

Differential Diagnoses

9

Conditions with similar clinical presentations that must be differentiated from Familial Nonmedullary Thyroid Carcinoma:

Classic familial adenomatous polyposis MONDO:0021055

Overlapping Features Germline APC variants cause familial adenomatous polyposis / Gardner syndrome, in which thyroid carcinoma - characteristically the cribriform-morular pattern, in young women - occurs alongside colorectal adenomatous polyposis. Identifying APC moves the family out of non-syndromic FNMTC and into a syndrome with its own colorectal surveillance and prophylactic colectomy pathway. See the Classic Familial Adenomatous Polyposis entry in this knowledge base.

Distinguishing Features

Colorectal adenomatous polyposis, often with congenital hypertrophy of the retinal pigment epithelium, desmoid tumors and osteomas.
Cribriform-morular thyroid carcinoma histology, strongly female-predominant and young-onset.
A pathogenic germline APC variant is identifiable, unlike in non-syndromic FNMTC.

Show evidence (1 reference)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Lists familial adenomatous polyposis among the syndromes that must be recognized and excluded.

Cowden syndrome MONDO:0016063

Overlapping Features Germline PTEN variants cause Cowden syndrome / PTEN hamartoma tumor syndrome, in which follicular and papillary thyroid carcinoma occur together with macrocephaly, mucocutaneous hamartomas, breast carcinoma and endometrial carcinoma. See the Cowden Syndrome and PTEN Hamartoma Tumor Syndrome entries, which already curate non-medullary thyroid carcinoma as a component phenotype.

Distinguishing Features

Macrocephaly, trichilemmomas and other mucocutaneous hamartomas.
Multi-organ tumor spectrum including breast and endometrial carcinoma.
A pathogenic germline PTEN variant is identifiable.

Show evidence (1 reference)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Lists Cowden syndrome among the syndromes that must be excluded before diagnosing non-syndromic FNMTC.

Carney complex Not Yet Curated MONDO:0015285

Overlapping Features Germline PRKAR1A variants cause Carney complex, in which thyroid follicular neoplasia occurs with lentigines, cardiac myxomas, primary pigmented nodular adrenocortical disease and other endocrine tumors.

Distinguishing Features

Spotty skin pigmentation (lentigines) and cardiac or cutaneous myxomas.
Primary pigmented nodular adrenocortical disease with Cushing syndrome.
A pathogenic germline PRKAR1A variant is identifiable.

Show evidence (1 reference)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Lists Carney complex type 1 among the syndromes that must be excluded.

Werner syndrome Not Yet Curated MONDO:0010196

Overlapping Features Biallelic germline WRN variants cause Werner syndrome, a segmental progeroid RecQ-helicase disorder with a characteristic neoplasm spectrum that includes thyroid carcinoma.

Distinguishing Features

Premature ageing phenotype with scleroderma-like skin, cataracts, short stature and early atherosclerosis.
Autosomal recessive rather than dominant transmission.
Biallelic pathogenic WRN variants are identifiable.

Show evidence (1 reference)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Lists Werner syndrome among the syndromes that must be excluded.

DICER1-related tumor predisposition Not Yet Curated MONDO:0100216

Overlapping Features Germline DICER1 variants cause a tumor predisposition syndrome in which multinodular goiter and differentiated thyroid carcinoma occur alongside pleuropulmonary blastoma, ovarian Sertoli-Leydig cell tumor and cystic nephroma.

Distinguishing Features

Pleuropulmonary blastoma, cystic nephroma or ovarian Sertoli-Leydig cell tumor in the pedigree.
Early-onset multinodular goiter, often before the carcinoma.
A pathogenic germline DICER1 variant is identifiable.

Show evidence (1 reference)

PMID:27807061 SUPPORT Human Clinical

"These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."

Lists DICER1 syndrome among the syndromes that must be excluded.

Medullary thyroid carcinoma MONDO:0015277

Overlapping Features Medullary thyroid carcinoma arises from calcitonin-producing parafollicular C cells, not from follicular cells, and its familial form (MEN2A, MEN2B, familial medullary thyroid carcinoma) is caused by germline RET variants with a well-defined genotype-directed prophylactic thyroidectomy pathway. It is excluded by definition from FNMTC and is curated separately in the Medullary Thyroid Carcinoma entry. Confusing the two is the principal named-entity hazard in this disease area.

Distinguishing Features

Parafollicular C cell rather than follicular cell origin.
Elevated serum calcitonin and carcinoembryonic antigen.
Germline RET variants with established genotype-risk-directed prophylactic thyroidectomy, unlike non-syndromic FNMTC where no such pathway exists.

Show evidence (1 reference)

PMID:31247975 SUPPORT Human Clinical

"Medullary thyroid carcinoma (MTC) develops from neuroendocrine C cells, and can occur sporadically or as a familial condition."

Establishes the C-cell origin that distinguishes medullary from non-medullary familial thyroid cancer.

Radiation-associated thyroid carcinoma

Overlapping Features Shared childhood neck irradiation within a family can produce apparent aggregation of thyroid carcinoma without inherited susceptibility. Excluding a common environmental exposure is part of the FNMTC definition.

Distinguishing Features

A documented history of therapeutic or accidental neck irradiation, typically in childhood, shared by affected relatives.
Aggregation follows the exposure rather than the pedigree structure.

Show evidence (1 reference)

PMID:33488516 SUPPORT Human Clinical

"which are observed in two or more first-degree relatives in the absence of predisposing environmental factors"

The definitional requirement to exclude a shared predisposing environmental exposure such as radiation.

Coincidental familial clustering of sporadic differentiated thyroid carcinoma Not Yet Curated MONDO:0015447

Overlapping Features Chance co-occurrence of sporadic papillary or follicular thyroid carcinoma within a family is the single most common alternative explanation for a two-affected-relative pedigree, and is the reason the two-relative definition is contested. Thyroid cancer is common and its detected incidence has risen sharply with ultrasound use, so a substantial fraction of two-case families do not represent inherited disease at all. Unlike the syndromic differentials this one cannot be excluded by a test - it is excluded probabilistically, by pedigree size.

Distinguishing Features

Exactly two affected first-degree relatives, with no third case and no unusually young onset.
Both cases detected incidentally during the ultrasound era rather than presenting clinically.
No excess of benign nodular thyroid disease among unaffected relatives.

Show evidence (2 references)

PMID:33025555 SUPPORT Human Clinical

"the presence of only two affected members in kindreds may represent a fortuitous association of the disease"

States the coincidental-clustering differential explicitly.

PMID:33025555 SUPPORT Human Clinical

"According to his mathematical simulation, 62–69% of 2-hit families are sporadic occurrences and thus, only families with 3 or more affected first-degree relatives should be considered for clinical and genetic investigations of FNMTC."

Quantifies how large this differential is - on the Charkes simulation the majority of two-case families fall into it.

Familial multinodular goiter Not Yet Curated MONDO:0000334

Overlapping Features Autosomal dominant familial multinodular goitre is common, especially in iodine-deficient regions, and can be mistaken for or coexist with FNMTC. Because benign nodular thyroid disease is itself enriched in FNMTC kindreds, a family with many nodular relatives and one or two carcinomas is genuinely ambiguous. Susceptibility to multinodular goitre and to non-medullary thyroid carcinoma may in fact be partly shared, so this is a boundary case rather than a clean exclusion.

Distinguishing Features

Nodular disease without histologically confirmed carcinoma in the affected relatives.
High background goitre prevalence in the population of origin (iodine deficiency).
Aggregation of goitre rather than of carcinoma across the pedigree.

Show evidence (2 references)

PMID:33025555 SUPPORT Human Clinical

"In areas with iodine deficiency MNG is common and, although the population incidence of MNG far exceeds that of thyroid cancer, there is also evidence that genetic susceptibility to MNG and to NMTC may be related"

Documents both the confounding and the possibility of genuinely shared susceptibility, which is why this is curated as a boundary case.

PMID:33025555 SUPPORT Human Clinical

"In fact, families segregating an autosomal dominant trait for MNG often include cases of NMTC."

States the co-segregation of multinodular goitre and non-medullary thyroid cancer within kindreds directly.

🔬

Clinical Trials

1

NCT01109420

The NIH prospective natural-history and screening cohort in familial non-medullary thyroid cancer, and the trial datum behind the central management question in this entry - whether to screen unaffected first-degree relatives. It enrols individuals aged 7 and over with two affected first-degree relatives, re-screens non-cancer participants yearly with non-invasive imaging, and is the source of the 4.6% versus 22.7% screening-yield gradient by pedigree size reported in PMID:28657510 and curated on the Surveillance Ultrasound diagnosis entry. Its stated objectives - natural history, best screening strategy, and susceptibility gene identification - map onto the three largest open questions in this entry.

Target Phenotypes: Non-medullary thyroid carcinoma HP:0040198 Thyroid nodule HP:0025388

Show evidence (2 references)

clinicaltrials:NCT01109420 SUPPORT Human Clinical

"To determine the best screening strategy for FNMTC."

The trial's own statement that relative-screening strategy is an unresolved question being studied prospectively - the registry-level counterpart to the unresolved screening recommendation curated here.

clinicaltrials:NCT01109420 SUPPORT Human Clinical

"Individuals at least 7 years of age who have two first-degree relatives (e.g., parents, children, siblings) who have or have had non-medullary thyroid cancer or a documented diagnosis of non-medullary thyroid cancer and one living relative with documented non-medullary thyroid cancer."

Documents that the cohort is assembled under the two-first-degree-relative definition, which is exactly the criterion questioned in the fnmtc-two-relative-definition discussion - so its yield estimates inherit that dilution.

{ }

Source YAML

click to show

name: Familial Nonmedullary Thyroid Carcinoma
creation_date: '2026-07-31T18:30:00Z'
description: >-
  Familial nonmedullary thyroid carcinoma (FNMTC) is the inherited predisposition
  to thyroid carcinoma arising from thyroid follicular cells (non-medullary,
  predominantly papillary histology). It is defined clinically by the occurrence
  of non-medullary thyroid carcinoma in two or more first-degree relatives in the
  absence of a recognized predisposing tumor syndrome and in the absence of shared
  antecedent ionizing-radiation exposure, and accounts for roughly 3-15% of
  non-medullary thyroid carcinoma depending on the case definition used. About 5%
  of familial cases are syndromic (familial adenomatous polyposis, Cowden/PTEN
  hamartoma tumor syndrome, Carney complex, Werner syndrome, DICER1 syndrome); the
  remaining ~95% are non-syndromic and are the subject of this entry. Non-syndromic
  FNMTC is not a single-gene Mendelian disease: it is markedly genetically
  heterogeneous, most often modeled as a polygenic trait built from multiple low-
  to moderate-penetrance susceptibility alleles, or as autosomal-dominant
  susceptibility with reduced, age-dependent penetrance and variable expressivity.
  Numerous candidate genes (FOXE1, SRGAP1, NKX2-1/TITF-1, SRRM2, MAP2K5, DUOX2,
  HABP2) and linkage loci (TCO/19p13.2, fPTC-PRN/1q21, NMTC1/2q21, MNG1/14q32,
  FTEN/8p23.1-p22, 6q22, 8q24) have been reported, but no single gene explains the
  majority of families and several reported associations have failed replication.
  Familial tumors are histologically indistinguishable from sporadic papillary and
  follicular carcinoma and carry the same somatic drivers, so FNMTC is best modeled
  as the familial predisposition layer sitting above the sporadic molecular
  entities rather than as a distinct tumor type.
synonyms:
- FNMTC
- Familial non-medullary thyroid cancer
- Familial nonmedullary thyroid gland carcinoma
- Familial papillary thyroid carcinoma
- Familial pure nonmedullary thyroid carcinoma
- Thyroid cancer, nonmedullary
categories:
- Endocrine Cancer
- Cancer Predisposition Syndrome
- Differentiated Thyroid Cancer
parents:
- thyroid carcinoma
- hereditary cancer-predisposing syndrome
disease_term:
  preferred_term: familial nonmedullary thyroid carcinoma
  term:
    id: MONDO:0017896
    label: familial nonmedullary thyroid carcinoma
classifications:
  harrisons_chapter:
  - classification_value: ONCOLOGY_HEMATOLOGY
    evidence:
    - reference: PMID:35255942
      reference_title: Genetic susceptibility to hereditary non-medullary thyroid cancer.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Non-medullary thyroid cancer (NMTC) is the most common type of thyroid cancer."
      explanation: FNMTC is the familial form of a follicular-cell-derived thyroid malignancy and belongs with oncology.
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:35255942
      reference_title: Genetic susceptibility to hereditary non-medullary thyroid cancer.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "This review summarizes genetic predisposition to non-medullary thyroid cancer and expands on the role of genetic variants in thyroid cancer tumorigenesis and the level of penetrance of NMTC-susceptibility genes."
      explanation: The entity is defined by inherited genetic predisposition, placing it in the genetics-of-disease part.
  icdo_morphology:
    classification_value: Carcinoma
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0017895
      label: familial papillary or follicular thyroid carcinoma
    mapping_predicate: skos:closeMatch
    mapping_source: MONDO (manual curation)
    mapping_justification: >-
      MONDO:0017895 ("familial papillary or follicular thyroid carcinoma", exact
      synonyms FNMTC and "familial nonmedullary thyroid gland carcinoma") is a
      direct child of MONDO:0017896 that it effectively duplicates, and MONDO
      itself tags it with `subset: obsoletion_candidate`. This entry therefore
      anchors `disease_term` on the parent MONDO:0017896 and records
      MONDO:0017895 as a close match rather than as a separate disease identity.
      The distinction MONDO:0017895 nominally adds - restricting to papillary or
      follicular histology - is not a real narrowing, because papillary and
      follicular carcinoma together constitute essentially all non-medullary
      thyroid carcinoma in familial series. Note that neither term cleanly hosts
      a syndromic-inclusive umbrella: MONDO:0017895 is an obsoletion candidate,
      and MONDO:0017896 is itself defined as "a rare non-syndromic form of
      thyroid cancer" and carries `subset: disease_grouping` /
      `subset: ordo_group_of_disorders`. Anchoring here is therefore the least
      bad option rather than an exact fit, which is why this entry scopes itself
      to the non-syndromic form and models the syndromic causes as differential
      diagnoses; see the `fnmtc-mondo-granularity` discussion.
inheritance:
- name: Polygenic Susceptibility
  description: >-
    Non-syndromic FNMTC is most commonly modeled as a polygenic trait in which
    multiple low- to moderate-penetrance susceptibility alleles combine to raise
    thyroid carcinoma risk, rather than as a single high-penetrance Mendelian
    locus. The best-replicated contributors are common GWAS risk alleles near
    FOXE1 (9q22.33) and NKX2-1 (14q13.3), each of modest individual effect. This
    inheritance model is why no validated predictive gene panel exists for
    isolated non-syndromic kindreds. Family-specific oligogenic combinations of
    rare alleles are a plausible alternative model for individual pedigrees but
    are not established as a general mechanism; see the open discussion on
    genetic architecture below.
  inheritance_term:
    preferred_term: Polygenic inheritance
    term:
      id: HP:0010982
      label: Polygenic inheritance
  penetrance: INCOMPLETE
  expressivity: VARIABLE
  evidence:
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "FNMTC is described as a polygenic disorder associated with multiple low- to moderate-penetrance susceptibility genes and incomplete penetrance."
    explanation: Directly supports the polygenic, low-to-moderate-penetrance model with incomplete penetrance.
  - reference: PMID:35295987
    reference_title: "Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Non-syndromic familial non-medullary carcinoma has a complex and heterogeneous genetic basis involving several genes and loci with a monogenic or polygenic inheritance model."
    explanation: Supports genetic heterogeneity with a polygenic (as well as monogenic) inheritance model.
  - reference: PMID:37175550
    reference_title: Identification of Novel Candidate Genes for Familial Thyroid Cancer by Whole Exome Sequencing.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although no common mutated genes were detected, biological processes regulating functions such as cell proliferation, differentiation, survival and adhesion were enriched."
    explanation: >-
      Contemporary whole-exome evidence (58 individuals from 18 families) for
      locus heterogeneity - no recurrent gene emerged, which is what the
      polygenic model predicts.
  - reference: PMID:37175550
    reference_title: Identification of Novel Candidate Genes for Familial Thyroid Cancer by Whole Exome Sequencing.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "familial NMTC shows a high degree of genetic heterogeneity"
    explanation: >-
      Explicit statement of the genetic heterogeneity that distinguishes
      familial non-medullary from familial medullary thyroid carcinoma, where
      germline RET explains the large majority of cases.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "more than 90% of familial cancers were in families with two affected members"
    explanation: >-
      Registry evidence for the pedigree-size distribution that favours a
      low-penetrance polygenic architecture over a high-penetrance Mendelian one.
- name: Autosomal Dominant Susceptibility With Reduced Penetrance
  description: >-
    Many individual kindreds segregate apparent autosomal-dominant susceptibility
    with reduced, age-dependent penetrance and variable expressivity. This
    pedigree-level pattern coexists with, rather than contradicts, the polygenic
    model: it is what a small number of rare moderate-penetrance alleles on a
    polygenic background looks like in a single large family, and it is the model
    under which the classic linkage loci (TCO, fPTC-PRN, NMTC1) were mapped.
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  penetrance: INCOMPLETE
  expressivity: VARIABLE
  evidence:
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "show an autosomal dominant pattern of inheritance with incomplete penetrance and variable expressivity"
    explanation: States the autosomal-dominant-with-incomplete-penetrance model for FNMTC kindreds.
  - reference: PMID:9837827
    reference_title: A gene predisposing to familial thyroid tumors with cell oxyphilia maps to chromosome 19p13.2.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The transmission of susceptibility to FNMTC is compatible with autosomal dominant inheritance with reduced penetrance, or with complex inheritance."
    explanation: The linkage study that mapped TCO states the dominant-with-reduced-penetrance (or complex) transmission model.
pathophysiology:
- name: Inherited Non-Syndromic Susceptibility in Thyroid Follicular Cells
  description: >-
    The upstream lesion in non-syndromic FNMTC is a constitutional (germline)
    susceptibility state in the thyroid follicular cell lineage, carried by a
    family-specific combination of common risk alleles and rare candidate
    variants rather than by one recurrent high-penetrance driver. Reported
    contributors include common risk variants near FOXE1 (9q22.33) and NKX2-1
    (14q13.3), rare segregating variants in SRGAP1, NKX2-1, FOXE1, SRRM2 and
    DUOX2, and susceptibility intervals mapped by linkage (TCO/19p13.2,
    fPTC-PRN/1q21, NMTC1/2q21, MNG1/14q32, FTEN/8p23.1-p22, 6q22, 8q24). Because
    each family tends to carry its own candidate lesion, this node is defined by
    the shared consequence - an inherited increase in follicular-cell cancer
    risk - rather than by a shared gene.
  biological_scale: MOLECULAR
  role: Trigger
  mechanism_confidence: PROVISIONAL
  cell_types:
  - preferred_term: thyroid follicular cell
    term:
      id: CL:0002258
      label: thyroid follicular cell
  locations:
  - preferred_term: thyroid gland
    term:
      id: UBERON:0002046
      label: thyroid gland
  genes:
  - preferred_term: FOXE1
    term:
      id: hgnc:3806
      label: FOXE1
  - preferred_term: NKX2-1
    term:
      id: hgnc:11825
      label: NKX2-1
  - preferred_term: SRGAP1
    term:
      id: hgnc:17382
      label: SRGAP1
  - preferred_term: SRRM2
    term:
      id: hgnc:16639
      label: SRRM2
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The causal genes located at the other 7 FNMTC-associated chromosomal loci (TCO (19q13.2), fPTC/ PRN (1q21), FTEN (8p23.1-p22), NMTC1 (2q21), MNG1 (14q32), 6q22, 8q24) have yet to be identified."
    explanation: Enumerates the classic FNMTC linkage loci and establishes that their causal genes remain unidentified.
  - reference: PMID:35255942
    reference_title: Genetic susceptibility to hereditary non-medullary thyroid cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although syndromic NMTC has well-known genetic risk factors, the gene(s) responsible for the vast majority of non-syndromic FNMTC cases are yet to be identified."
    explanation: Establishes that the upstream germline lesion for most non-syndromic families is not attributable to a known gene.
  - reference: PMID:38571492
    reference_title: Chromosomal localization of mutated genes in non-syndromic familial thyroid cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "But FNMTC exhibits strong genetic heterogeneity, with each family having its own pathogenic genes."
    explanation: Supports modeling the trigger as a family-specific susceptibility state rather than one shared gene.
  - reference: PMID:35255942
    reference_title: Genetic susceptibility to hereditary non-medullary thyroid cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the familial risk ratio of NMTC in affected first-degree relatives is 5.2 for men and 4.9 for women"
    explanation: >-
      Quantifies the magnitude of the inherited component from a national
      registry cohort - the empirical justification for treating FNMTC as a
      disease concept even though its molecular basis is unresolved.
  - reference: PMID:35255942
    reference_title: Genetic susceptibility to hereditary non-medullary thyroid cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prevalence of NMTC in the general population and in first-degree relatives of NMTC patients were 0.16% and 0.64%, respectively."
    explanation: >-
      Independent Taiwanese cohort of 38,686 patients giving the absolute
      prevalences behind the 5.47-fold first-degree-relative risk.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "If a parent was affected, risk for offspring was threefold for thyroid cancer."
    explanation: >-
      Swedish Family Cancer Database estimate (14.7 million individuals) of
      parent-to-offspring thyroid cancer risk.
  downstream:
  - target: Perturbed Thyroid Transcription Factor and Growth-Regulatory Signaling
    description: >-
      Rare segregating variants in thyroid developmental transcription factors
      and growth regulators act directly in the follicular cell.
    causal_link_type: DIRECT
  - target: Telomere-Telomerase Imbalance and Chromosome Fragility
    description: >-
      Familial cases show a constitutional telomere-telomerase imbalance whose
      causal genes are not identified, so the link is indirect.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - telomere_length_predisposition
  - target: HABP2 G534E Loss of Tumor-Suppressor Function
    description: >-
      Contested branch - proposed as the germline lesion in one kindred but
      not replicated. Modelled only under the DEPRECATED
      habp2_g534e_susceptibility hypothesis group.
    causal_link_type: DIRECT
    hypothesis_groups:
    - habp2_g534e_susceptibility
- name: Perturbed Thyroid Transcription Factor and Growth-Regulatory Signaling
  description: >-
    Functionally characterized FNMTC candidate variants converge on loss of normal
    restraint over follicular-cell proliferation and differentiation. The germline
    NKX2-1/TITF-1 A339V variant increases proliferation and thyrotropin-independent
    growth while impairing transcription of the thyroid-differentiation genes Tg,
    TSH-R and Pax-8; a germline FOXE1 p.A248G variant promotes proliferation and
    migration; SRGAP1 variants abolish the protein's ability to inactivate CDC42,
    a Rho-family GTPase controlling cytoskeletal and growth signaling; and an
    SRRM2 splicing-factor variant shifts alternative splicing of downstream
    targets. Individually these are low-penetrance or family-specific effects, but
    they share the outcome of a follicular cell that is more permissive to
    transformation.
  biological_scale: CELLULAR
  role: Intermediate
  mechanism_confidence: PROVISIONAL
  cell_types:
  - preferred_term: thyroid follicular cell
    term:
      id: CL:0002258
      label: thyroid follicular cell
  biological_processes:
  - preferred_term: cell population proliferation
    modifier: INCREASED
    term:
      id: GO:0008283
      label: cell population proliferation
  - preferred_term: Ras protein signal transduction
    modifier: INCREASED
    term:
      id: GO:0007265
      label: Ras protein signal transduction
  genes:
  - preferred_term: NKX2-1
    term:
      id: hgnc:11825
      label: NKX2-1
  - preferred_term: FOXE1
    term:
      id: hgnc:3806
      label: FOXE1
  - preferred_term: SRGAP1
    term:
      id: hgnc:17382
      label: SRGAP1
  evidence:
  - reference: PMID:19176457
    reference_title: A germline mutation (A339V) in thyroid transcription factor-1 (TITF-1/NKX2.1) in patients with multinodular goiter and papillary thyroid carcinoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Overexpression of A339V TTF-1 in PCCL3 cells, as compared with overexpression of WT TTF-1, was associated with increased cell proliferation including thyrotropin-independent growth"
    explanation: Functional assay in normal rat thyroid cells shows the germline TTF-1 variant increases proliferation and confers TSH independence.
  - reference: PMID:23539728
    reference_title: SRGAP1 is a candidate gene for papillary thyroid carcinoma susceptibility.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Biochemical assays demonstrated that the ability to inactivate CDC42, a key function of SRGAP1, was severely impaired by the Q149H and R617C variants."
    explanation: Establishes the molecular consequence of segregating SRGAP1 variants as loss of CDC42 inactivation.
  - reference: PMID:25381600
    reference_title: Identification of a novel germline FOXE1 variant in patients with familial non-medullary thyroid carcinoma (FNMTC).
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we observed that the p.A248G variant promoted cell proliferation and migration, suggesting that it may be involved in thyroid tumorigenesis"
    explanation: Functional evidence that a segregating germline FOXE1 variant increases follicular-cell proliferation and migration.
  - reference: PMID:26135620
    reference_title: A germline mutation in SRRM2, a splicing factor gene, is implicated in papillary thyroid carcinoma predisposition.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These data suggest that the S346F mutation in SRRM2 predisposes to PTC by affecting alternative splicing of unidentified downstream target genes."
    explanation: Supports a splicing-mediated predisposition arm within this node, with the downstream targets explicitly unidentified.
  downstream:
  - target: Acquisition of Somatic MAPK-Activating Driver Alterations
    description: >-
      A proliferation-permissive, less-differentiated follicular cell is more
      likely to fix and expand a somatic MAPK-activating driver.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Telomere-Telomerase Imbalance and Chromosome Fragility
  description: >-
    Patients with familial papillary thyroid carcinoma show a constitutional
    imbalance of the telomere-telomerase complex in peripheral blood - shorter
    relative telomere length than sporadic cases, unaffected siblings and healthy
    controls, together with hTERT/TERT gene amplification and increased telomerase
    activity. The same familial cohorts show a significant excess of spontaneous
    telomeric associations and telomeric fusions, i.e. measurable constitutional
    chromosome instability. This arm is a candidate constitutional mechanism of
    predisposition, distinct from the tumor-intrinsic telomere-maintenance
    reactivation (TERT promoter mutation) seen in advanced sporadic thyroid cancer.
  biological_scale: CELLULAR
  role: Intermediate
  mechanism_confidence: HYPOTHETICAL
  conforms_to: "genome_instability_mutation#Mutator Phenotype and Chromosomal Instability"
  notes: >-
    Conformance to genome_instability_mutation#Mutator Phenotype and Chromosomal
    Instability is declared on the strength of the directly measured
    constitutional chromosomal instability in familial cases (excess spontaneous
    telomeric associations and fusions), which is the "chromosomal instability
    with structural rearrangements" manifestation the module node describes. The
    conformance is deliberately partial: the module's upstream arm posits a
    genome-maintenance/DNA-repair defect (GO:0006281 DNA repair, DECREASED), and
    no such repair defect has been demonstrated in non-syndromic FNMTC, so that
    process is not asserted here. The instability is instead approached through
    the telomere-telomerase axis, and mechanism_confidence is set to HYPOTHETICAL
    to reflect that its causal role in predisposition is proposed rather than
    established.
  biological_processes:
  - preferred_term: telomere maintenance
    modifier: ABNORMAL
    term:
      id: GO:0000723
      label: telomere maintenance
  - preferred_term: telomere maintenance via telomerase
    modifier: INCREASED
    term:
      id: GO:0007004
      label: telomere maintenance via telomerase
  genes:
  - preferred_term: TERT
    term:
      id: hgnc:11730
      label: TERT
  evidence:
  - reference: PMID:18664542
    reference_title: "Short telomeres, telomerase reverse transcriptase gene amplification, and increased telomerase activity in the blood of familial papillary thyroid cancer patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our study demonstrates that patients with FPTC display an imbalance of the telomere-telomerase complex in the peripheral blood, characterized by short telomeres, hTERT gene amplification, and expression."
    explanation: Direct human evidence for the constitutional telomere-telomerase imbalance modeled by this node.
  - reference: PMID:18664542
    reference_title: "Short telomeres, telomerase reverse transcriptase gene amplification, and increased telomerase activity in the blood of familial papillary thyroid cancer patients."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "These features may be implicated in the inherited predisposition to develop FPTC."
    explanation: The authors themselves frame the causal role in predisposition as a possibility, so the predisposition claim is only partially supported.
  - reference: PMID:22539583
    reference_title: Telomere abnormalities and chromosome fragility in patients affected by familial papillary thyroid cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We demonstrate that fPTC patients have a significant increase in spontaneous telomeric associations and telomeric fusions compared with healthy subjects and sporadic cases in the frame of an otherwise common spontaneous chromosome fragility pattern."
    explanation: Supports measurable constitutional chromosomal instability in familial cases, the basis for the genome_instability_mutation conformance.
  downstream:
  - target: Acquisition of Somatic MAPK-Activating Driver Alterations
    description: >-
      Constitutional telomeric instability plausibly raises the rate at which
      follicular cells acquire and fix oncogenic somatic alterations.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - telomere_length_predisposition
- name: Acquisition of Somatic MAPK-Activating Driver Alterations
  description: >-
    Familial and sporadic non-medullary thyroid carcinoma share the same
    morphology and the same somatic driver landscape - BRAF V600E, RAS-family
    mutations, RET/PTC and NTRK fusions - so the germline susceptibility layer
    does not create a distinct tumor genotype; it raises the probability that a
    follicular cell acquires one of the ordinary MAPK-activating drivers, and it
    does so in many cells at once, which is the mechanistic basis for the excess
    multifocality and bilaterality of familial tumors. Somatic BRAF V600E has been
    documented in the tumors of family members carrying a segregating germline
    FOXE1 variant, directly illustrating the germline-plus-somatic two-layer model.
    The somatic driver biology itself is curated in the sporadic entries
    (Papillary Thyroid Carcinoma, Thyroid Follicular Carcinoma,
    BRAF Mutant Thyroid Cancer, RET Fusion Thyroid Cancer) and is not duplicated
    here.
  biological_scale: MOLECULAR
  role: Intermediate
  mechanism_confidence: PROVISIONAL
  cell_types:
  - preferred_term: thyroid follicular cell
    term:
      id: CL:0002258
      label: thyroid follicular cell
  biological_processes:
  - preferred_term: MAPK cascade
    modifier: INCREASED
    term:
      id: GO:0000165
      label: MAPK cascade
  - preferred_term: phosphatidylinositol 3-kinase/protein kinase B signal transduction
    modifier: INCREASED
    term:
      id: GO:0043491
      label: phosphatidylinositol 3-kinase/protein kinase B signal transduction
  evidence:
  - reference: PMID:35295987
    reference_title: "Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Given that non-syndromic familial non-medullary carcinoma and sporadic non-medullary thyroid carcinoma share the same morphology and somatic mutations, the same targeted therapies could be used at present"
    explanation: Establishes that the somatic driver layer of familial tumors is the same as that of sporadic tumors.
  - reference: PMID:25381600
    reference_title: Identification of a novel germline FOXE1 variant in patients with familial non-medullary thyroid carcinoma (FNMTC).
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Additionally, somatic p.V600E BRAF mutations were also detected in the thyroid tumors of two members of the family carrying the p.A248G variant."
    explanation: Worked example of the germline-susceptibility-plus-somatic-MAPK-driver two-layer model within a single FNMTC kindred.
  - reference: PMID:37438605
    reference_title: Pathogenesis of cancers derived from thyroid follicular cells.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Essentially, the main oncoproteins in thyroid cancer activate nodes in the receptor tyrosine kinase-RAS-BRAF pathway, which constitutively induces MAPK signalling to varying degrees consistent with their specific biochemical mechanisms of action."
    explanation: >-
      Authoritative review establishing that the follicular-cell thyroid cancer
      drivers converge on constitutive MAPK signalling - the mechanistic anchor
      for this node's GO:0000165 annotation.
  - reference: PMID:26222560
    reference_title: Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "We also found no somatic mutations or known rearrangements in BRAF, KRAS, NRAS, or RET/PTC1 and RET/PTC3 in the tumor samples (Table 1)."
    explanation: >-
      A bounding counterexample rather than a confirmation - a familial kindred
      whose tumors carried none of the common sporadic drivers. Tagged PARTIAL
      because it constrains, rather than supports, the claim that the familial
      and sporadic driver landscapes are identical, and is the reason
      mechanism_confidence here is PROVISIONAL.
  downstream:
  - target: Multifocal Follicular Cell Transformation
    description: Constitutive mitogenic signaling drives clonal expansion and transformation.
    causal_link_type: DIRECT
- name: Multifocal Follicular Cell Transformation
  description: >-
    Transformation occurs against a field of inherited susceptibility, so it is
    characteristically multicentric and bilateral, frequently accompanied by
    benign follicular adenoma and multinodular goiter in the same gland and in
    unaffected relatives. Tumors then follow the ordinary differentiated
    thyroid-cancer natural history - intrathyroidal growth, extrathyroidal
    extension, cervical nodal spread and, less often, distant metastasis - with
    familial series showing a more aggressive presentation at diagnosis but not a
    worse outcome after appropriate treatment.
  biological_scale: TISSUE
  role: Consequence
  mechanism_confidence: ESTABLISHED
  cell_types:
  - preferred_term: thyroid follicular cell
    term:
      id: CL:0002258
      label: thyroid follicular cell
  locations:
  - preferred_term: thyroid gland
    term:
      id: UBERON:0002046
      label: thyroid gland
  evidence:
  - reference: PMID:35295987
    reference_title: "Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Most cases are papillary thyroid carcinoma (classic and follicular variant), usually accompanied by benign thyroid nodules (follicular thyroid adenoma and/or multinodular goiter)."
    explanation: Supports the multifocal thyroid-neoplasia field, malignant and benign, that characterizes the transformed gland in FNMTC.
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We found that familial tumors had a statistically significant more aggressive presentation at diagnosis, though not resulting in a worst outcome."
    explanation: Supports the more aggressive presentation with preserved outcome that characterizes the clinical consequence node.
  downstream:
  - target: Papillary Thyroid Carcinoma
    description: The dominant malignant histology in familial kindreds.
    causal_link_type: DIRECT
  - target: Follicular Thyroid Carcinoma
    description: A minority of familial tumors are follicular-patterned carcinoma.
    causal_link_type: DIRECT
  - target: Multifocal and Bilateral Thyroid Carcinoma
    description: Field predisposition produces multicentric and bilateral disease.
    causal_link_type: DIRECT
  - target: Benign Thyroid Nodules and Multinodular Goiter
    description: Benign follicular neoplasia accompanies the malignant field.
    causal_link_type: DIRECT
  - target: Cervical Lymphadenopathy
    description: Regional nodal spread from the primary tumor.
    causal_link_type: DIRECT
  - target: Extrathyroidal Extension
    description: Locally invasive growth beyond the thyroid capsule.
    causal_link_type: DIRECT
  - target: Pulmonary Metastasis
    description: Distant haematogenous spread in a minority of familial cases.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
  - target: Earlier Age at Onset in Successive Generations
    description: >-
      Observed clinical anticipation, at least partly confounded by ascertainment
      and surveillance intensity.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_anticipation
- name: HABP2 G534E Loss of Tumor-Suppressor Function
  description: >-
    CONTESTED - retained as a modelled but refuted branch, not part of the
    canonical FNMTC mechanism. In 2015 a germline HABP2 c.1601G>A (p.G534E)
    variant was reported to segregate with disease in all seven affected members
    of one FNMTC kindred, to be present in 4.7% of 423 TCGA papillary thyroid
    cancers, and to behave as a dominant-negative loss of a tumor-suppressive
    function in colony-formation, foci and migration assays performed in
    NIH-3T3 fibroblasts rather than in thyroid cells. One independent kindred
    series supported a susceptibility role in a subgroup. Multiple independent
    replication studies then contradicted causality on three separate grounds:
    failure of cosegregation within carrier families, population carrier
    frequencies of 7.6-9.3% that are incompatible with a highly penetrant
    dominant allele, and absence of HABP2 expression in thyroid tissue. This
    node exists so that the DEPRECATED habp2_g534e_susceptibility hypothesis
    group is wired to real causal edges and the controversy stays auditable
    rather than being silently deleted.
  biological_scale: MOLECULAR
  role: Disputed Branch
  mechanism_confidence: HYPOTHETICAL
  cell_types:
  - preferred_term: thyroid follicular cell
    term:
      id: CL:0002258
      label: thyroid follicular cell
  genes:
  - preferred_term: HABP2
    term:
      id: hgnc:4798
      label: HABP2
  evidence:
  - reference: PMID:26222560
    reference_title: Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Since we did not find alterations in the other HABP2 allele in the tumor tissue and our functional studies suggested that HABP2 has a tumor-suppressive effect, we cotransfected equal amounts of the wild-type and G534E mutant constructs into NIH-3T3 cells."
    explanation: >-
      The original functional claim - a dominant-negative effect on a
      tumor-suppressive HABP2 function, demonstrated in fibroblasts rather than
      in thyroid cells.
  - reference: PMID:26222560
    reference_title: Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Finally, analysis of TCGA data in 423 patients with papillary thyroid cancer showed that 4.7% carried the HABP2 G534E variant, as compared with 0.7% of persons with unknown disease status in multiethnic population databases (P<0.001)."
    explanation: The case-control frequency argument offered in the original report.
  - reference: PMID:26832773
    reference_title: HABP2 G534E Mutation in Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These results are consistent with HABP2 G534E being a susceptibility gene in a subgroup of FNMTC, providing important diagnostic implications for this hereditary thyroid cancer."
    explanation: >-
      The principal independent report favouring a susceptibility role, so both
      sides of the controversy are represented rather than only the refutations.
  - reference: PMID:26745718
    reference_title: HABP2 G534E Variant in Papillary Thyroid Carcinoma.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "The variant did not segregate with PTC in one large and 6 smaller families in which it occurred."
    explanation: >-
      Segregation failure across seven families - the core genetic argument
      against causality.
  - reference: PMID:26745718
    reference_title: HABP2 G534E Variant in Papillary Thyroid Carcinoma.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "The variant was found to be present in 6.1% familial cases, 8.0% sporadic cases (2 individuals were homozygous for the variant) and 8.7% controls."
    explanation: >-
      Case and control frequencies are indistinguishable, contradicting the
      enrichment reported in the original study.
  - reference: PMID:26745718
    reference_title: HABP2 G534E Variant in Papillary Thyroid Carcinoma.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "In keeping with data from the literature and databases the expression of HABP2 was highest in the liver, much lower in 3 other tested tissues (breast, kidney, brain) but not found in thyroid."
    explanation: >-
      HABP2 is not expressed in thyroid, a strong biological argument against
      any thyroid-autonomous tumour-suppressor role.
  - reference: PMID:26906432
    reference_title: HABP2 Gene Mutations Do Not Cause Familial or Sporadic Non-Medullary Thyroid Cancer in a Highly Inbred Middle Eastern Population.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "None of the familial NMTC carried HABP2 mutations. Of 509 sporadic NMTC, only one case (0.2%) harbored the G534E variant."
    explanation: Complete failure to replicate in familial cases and in 509 sporadic cancers.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "All these studies failed in detecting the p.G534E mutation in FNMTC suggesting that Gara et al. identified a private variation"
    explanation: Review-level synthesis reaching the private-variant conclusion.
  downstream:
  - target: Multifocal Follicular Cell Transformation
    description: >-
      Proposed but unreplicated route from HABP2 loss of function to malignant
      transformation of the follicular epithelium.
    causal_link_type: UNKNOWN
    hypothesis_groups:
    - habp2_g534e_susceptibility
mechanistic_hypotheses:
- hypothesis_group_id: habp2_g534e_susceptibility
  hypothesis_label: HABP2 p.G534E as an FNMTC susceptibility allele
  status: DEPRECATED
  description: >-
    Proposed in 2015 on the basis of cosegregation in a single kindred,
    enrichment in TCGA papillary thyroid cancers (4.7% versus 0.7%), and
    dominant-negative functional assays; supported in one independent kindred
    series. Contradicted by at least four independent replication studies on
    three grounds: failure of cosegregation within families carrying the
    variant, population carrier frequencies of 7.6-9.3% incompatible with a
    high-penetrance allele, and absence of HABP2 expression in thyroid tissue.
    Marked DEPRECATED because the weight of replication is against a causal
    role and contemporary reviews treat G534E as a common polymorphism or a
    private variation rather than an FNMTC gene. Retained explicitly rather
    than deleted, because the controversy is itself instructive and the
    supporting reports remain in the literature. The narrow residual question -
    whether the allele could act as a very-low-penetrance modifier in some
    ancestries - is tracked in the fnmtc-habp2-controversy discussion.
  evidence:
  - reference: PMID:26222560
    reference_title: Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our findings suggest that HABP2 is a susceptibility gene for thyroid cancer of follicular-cell origin."
    explanation: The originating claim.
  - reference: PMID:26745718
    reference_title: HABP2 G534E Variant in Papillary Thyroid Carcinoma.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Given these results showing lack of any involvement we suggest that the putative role of variant HABP2 in PTC should be carefully scrutinized."
    explanation: The most-cited refutation.
  - reference: PMID:26906432
    reference_title: HABP2 Gene Mutations Do Not Cause Familial or Sporadic Non-Medullary Thyroid Cancer in a Highly Inbred Middle Eastern Population.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "In this study, HABP2 mutations were not found in familial NMTC, and the G534E variant is not the underlying genetic defect in a large sample of sporadic NMTC from the Middle East."
    explanation: Independent non-replication in a large familial and sporadic series.
- hypothesis_group_id: telomere_length_predisposition
  hypothesis_label: Germline telomere-length dysregulation as an FNMTC predisposition mechanism
  status: EMERGING
  description: >-
    Two directionally opposite versions of a telomere hypothesis coexist in
    this entry and are deliberately both curated. The older version holds that
    familial papillary thyroid cancer patients carry SHORTER germline and
    somatic telomeres with hTERT amplification and excess spontaneous telomeric
    associations and fusions - the constitutional chromosome-fragility arm
    modelled by the Telomere-Telomerase Imbalance and Chromosome Fragility
    node; support is inconsistent, with at least one study finding no
    difference between familial and sporadic cases. The newer and
    better-powered version holds that germline LENGTHENING variants in the
    shelterin proteins POT1, TINF2 and ACD define a syndromic long-telomere
    papillary thyroid cancer subtype present in 4.5% of familial cases, with
    the mechanism being an expanded replicative reserve. The two point in
    opposite directions but are not strictly incompatible: shelterin variants
    account for only a small minority of familial cases, so the two literatures
    may simply describe different subgroups. Status EMERGING because the
    relationship is unresolved.
  evidence:
  - reference: PMID:38688277
    reference_title: Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We tested whether variants in POT1 and four other telomere-maintenance genes associated with familial cancer underlie PTC susceptibility."
    explanation: The telomere-lengthening arm of the hypothesis.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Some studies have demonstrated that FNMTC patients have shorter germline and somatic telomere length suggesting the role of telomere shortening in the development of FNMTC"
    explanation: >-
      Records the older telomere-SHORTENING arm, which reports the opposite
      direction of effect from the shelterin literature.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "However, another study did not shown any differences in telomere length and telomerase activity between familial and sporadic PTC cases"
    explanation: Records the inconsistency within the telomere-shortening arm itself.
- hypothesis_group_id: clinical_anticipation
  hypothesis_label: Genetic anticipation in FNMTC across generations
  status: ALTERNATIVE
  description: >-
    Several series report that the second generation of parent-child FNMTC
    kindreds presents at an earlier age, with more multifocal and bilateral
    tumours, more nodal metastases and worse outcome than the first generation,
    and a six-study meta-analysis confirms a younger age of onset in the second
    generation. No repeat expansion or other molecular anticipation mechanism
    has been demonstrated; the one candidate substrate is progressive
    intergenerational telomere lengthening in shelterin-variant kindreds, which
    applies to only a small minority of families. The competing explanation is
    structural: once a parent is diagnosed, offspring enter surveillance and are
    therefore diagnosed earlier and at smaller size by construction, and
    prospective screening data confirm that this mechanism operates. Curated as
    ALTERNATIVE and never CANONICAL - the observation is real, but its
    interpretation as true genetic anticipation is not established.
  evidence:
  - reference: PMID:18832444
    reference_title: Familial non-medullary thyroid carcinoma displays the features of clinical anticipation suggestive of a distinct biological entity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In conclusion, FNMTC displays the features of clinical 'anticipation' with the second generation acquiring the disease at an earlier age and having more advanced disease at presentation."
    explanation: The originating observation of clinical anticipation in FNMTC.
  - reference: PMID:28942234
    reference_title: "Second generation of familial nonmedullary thyroid carcinoma: A meta-analysis on the clinicopathologic features and prognosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thus we conclude that the second generation of parent/offspring type FNMTC patients is in higher risk than their first generation counterpart."
    explanation: Meta-analytic confirmation of the generational difference.
  - reference: PMID:38688277
    reference_title: Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Successive generations had longer telomere length than their parents and, at times, developed more cancers at younger ages."
    explanation: >-
      The only reported molecular substrate that could make anticipation genuine
      in a subset of families - progressive intergenerational telomere
      lengthening, distinct from a repeat expansion.
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "FNMTC detected by screening was characterized by a smaller tumor size"
    explanation: >-
      Demonstrates the ascertainment mechanism that can generate apparent
      anticipation - surveillance shifts detection earlier and to smaller
      tumours independently of any change in biology. Tagged PARTIAL, not
      REFUTE, because the study is a screening-yield analysis and never
      addresses anticipation directly.
phenotypes:
- category: Neoplasm
  name: Non-Medullary Thyroid Carcinoma
  description: >-
    The defining phenotype of the entity - thyroid carcinoma arising from
    follicular cells. Medullary thyroid carcinoma of parafollicular C-cell
    origin is explicitly excluded, which is why this HPO term rather than the
    generic thyroid-carcinoma parent is used as the disease-defining descriptor.
  frequency: OBLIGATE
  diagnostic: true
  phenotype_term:
    preferred_term: Non-medullary thyroid carcinoma
    term:
      id: HP:0040198
      label: Non-medullary thyroid carcinoma
  evidence:
  - reference: PMID:26222560
    reference_title: Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thyroid cancers of follicular-cell origin account for more than 95% of all cases of thyroid cancer, with the remaining cancers originating from parafollicular cells (medullary thyroid cancer)."
    explanation: >-
      Defines the follicular-cell versus parafollicular-cell boundary that makes
      "non-medullary" the operative disease-defining phenotype.
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The term familial non-medullary thyroid cancers (FNMTCs) is used to indicate thyroid tumors, arising from follicular cells, which are observed in two or more first-degree relatives in the absence of predisposing environmental factors."
    explanation: >-
      Confirms follicular-cell origin as definitional, supporting the OBLIGATE
      frequency band.
- category: Neoplasm
  name: Papillary Thyroid Carcinoma
  description: >-
    Papillary carcinoma is the dominant histology in familial kindreds, in classic
    and follicular-variant forms, and is morphologically indistinguishable from
    sporadic papillary thyroid carcinoma.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Papillary thyroid carcinoma
    term:
      id: HP:0002895
      label: Papillary thyroid carcinoma
  evidence:
  - reference: PMID:35295987
    reference_title: "Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Most cases are papillary thyroid carcinoma (classic and follicular variant), usually accompanied by benign thyroid nodules (follicular thyroid adenoma and/or multinodular goiter)."
    explanation: Supports papillary carcinoma as the predominant (very frequent) histology of non-syndromic FNMTC.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Familial non-medullary thyroid carcinoma (FNMTC), mainly of papillary histotype (FPTC), is defined by the presence of the disease in two or more first-degree relatives in the absence of other known familial syndromes."
    explanation: Confirms the papillary histotype predominance that justifies the VERY_FREQUENT band.
- category: Neoplasm
  name: Follicular Thyroid Carcinoma
  description: >-
    A minority of familial non-medullary tumors are follicular carcinoma; oncocytic
    (Hurthle cell) carcinoma is rarer still and defines the TCO branch of the
    linkage literature, in which thyroid tumors show cell oxyphilia.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Follicular thyroid carcinoma
    term:
      id: HP:0006731
      label: Follicular thyroid carcinoma
  evidence:
  - reference: PMID:9837827
    reference_title: A gene predisposing to familial thyroid tumors with cell oxyphilia maps to chromosome 19p13.2.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC."
    explanation: Documents non-papillary (oxyphilic follicular) malignant histology within an FNMTC kindred.
- category: Neoplasm
  name: Multifocal and Bilateral Thyroid Carcinoma
  description: >-
    Familial tumors are more often multicentric and bilateral than matched sporadic
    papillary carcinoma, consistent with transformation arising in a field of
    inherited susceptibility rather than from a single clone.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Multifocal thyroid carcinoma
    term:
      id: HP:0002890
      label: Thyroid carcinoma
  evidence:
  - reference: PMID:26191611
    reference_title: Clinicopathological features and prognosis of familial papillary thyroid carcinoma--a large-scale, matched, case-control study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Compared with sporadic PTC, patients with FPTC were more likely to present tumour multicentricity, bilateral growth and a concomitant nodular goitre"
    explanation: Matched case-control study of 372 familial versus 372 sporadic papillary carcinomas supports excess multicentricity and bilaterality.
  - reference: PMID:18832444
    reference_title: Familial non-medullary thyroid carcinoma displays the features of clinical anticipation suggestive of a distinct biological entity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Significant difference between sporadic PTC and FNMTC patients included more frequent tumor multifocality (P=0.001) and worse final outcome in FNMTC patients (P=0.001)."
    explanation: Independent cohort comparison supporting excess multifocality in familial versus sporadic disease.
  - reference: PMID:11438887
    reference_title: Localization of a susceptibility gene for familial nonmedullary thyroid carcinoma to chromosome 2q21.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The familial form of nonmedullary thyroid carcinoma (NMTC) is a complex genetic disorder characterized by multifocal neoplasia and a higher degree of aggressiveness than its sporadic counterpart."
    explanation: Independently characterizes multifocal neoplasia as a defining clinical feature of familial NMTC.
- category: Neoplasm
  name: Benign Thyroid Nodules and Multinodular Goiter
  description: >-
    Benign follicular adenoma and multinodular goiter frequently accompany the
    malignant tumor in the same gland and are also enriched among unaffected
    relatives, which is why nodule detection - rather than a symptom - is the usual
    presentation.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Multinodular goiter
    term:
      id: HP:0005987
      label: Multinodular goiter
  evidence:
  - reference: PMID:35295987
    reference_title: "Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "usually accompanied by benign thyroid nodules (follicular thyroid adenoma and/or multinodular goiter)"
    explanation: States that benign nodular disease usually accompanies the familial carcinoma.
  - reference: PMID:9837827
    reference_title: A gene predisposing to familial thyroid tumors with cell oxyphilia maps to chromosome 19p13.2.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cases of benign thyroid disease are often found in FNMTC kindreds."
    explanation: Independently supports the enrichment of benign thyroid disease within FNMTC families.
- category: Neoplasm
  name: Thyroid Nodule
  description: >-
    The usual clinical presentation is an asymptomatic thyroid nodule found on
    palpation or, increasingly, on ultrasound performed because of family
    history. Split out from the bundled benign-nodule/goiter phenotype above so
    that the discrete nodule - the actual index lesion, and the object of the
    0.5 cm biopsy threshold used in FNMTC screening cohorts - is separately
    queryable from diffuse multinodular goiter. Nodules are also common in
    unaffected relatives, which is what makes screening yield hard to interpret.
    No frequency band is asserted: the cited evidence describes a screening
    protocol rather than quantifying nodule prevalence in FNMTC.
  phenotype_term:
    preferred_term: Thyroid nodule
    term:
      id: HP:0025388
      label: Thyroid nodule
  evidence:
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A prospective cohort study was performed with yearly screening using neck ultrasound and fine-needle aspiration biopsy of thyroid nodule(s) >0.5 cm in at-risk individuals whose relatives were diagnosed with familial non-medullary thyroid cancer (FNMTC)."
    explanation: >-
      Documents the thyroid nodule as the screening target and index lesion in
      at-risk FNMTC relatives, and the size threshold applied to it.
- category: Systemic
  name: Cervical Lymphadenopathy
  description: >-
    Regional cervical nodal metastasis is common at presentation and is reported
    more often in second-generation than first-generation affected family members.
  phenotype_term:
    preferred_term: Cervical lymphadenopathy
    term:
      id: HP:0025289
      label: Cervical lymphadenopathy
  evidence:
  - reference: PMID:18832444
    reference_title: Familial non-medullary thyroid carcinoma displays the features of clinical anticipation suggestive of a distinct biological entity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "their tumors were more frequently multifocal (P=0.003) and bilateral (P=0.01), had higher rate of lymph node metastases at surgery (P=0.02) and worse outcome (P=0.04) when compared with the first generation"
    explanation: Documents cervical nodal metastasis in familial kindreds and its generational gradient.
- category: Neoplasm
  name: Extrathyroidal Extension
  description: >-
    Locally invasive growth beyond the thyroid capsule is part of the more
    aggressive presentation reported for familial tumors at diagnosis; it does not
    translate into worse disease-specific outcome once treated appropriately.
  phenotype_term:
    preferred_term: Neoplasm of the thyroid gland
    term:
      id: HP:0100031
      label: Neoplasm of the thyroid gland
  notes: >-
    HPO has no term for extrathyroidal extension specifically, so the descriptor is
    bound to the nearest available thyroid-neoplasm parent and the invasive
    behaviour is carried by preferred_term and description.
  evidence:
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "We found that familial tumors had a statistically significant more aggressive presentation at diagnosis, though not resulting in a worst outcome."
    explanation: >-
      Supports the aggressive local presentation of which extrathyroidal extension
      is a component; the abstract does not itself break out the extension rate, so
      support is partial.
- category: Neoplasm
  name: Pulmonary Metastasis
  description: >-
    Distant metastasis, most often pulmonary, occurs in a minority of familial
    cases and follows the ordinary differentiated thyroid-cancer pattern. It is
    uncommon in absolute terms but carries the largest familial-versus-sporadic
    effect size of any feature in FNMTC, and - unlike tumour size or nodal
    status - is the least plausible product of earlier detection, so it is the
    strongest single argument that some of the familial aggressiveness signal is
    real biology rather than surveillance artefact.
  notes: >-
    No `frequency:` band is asserted. The available quantitative source
    (PMID:40908394) reports a relative measure - pooled odds ratios versus
    sporadic disease - not an absolute rate, and no cached abstract gives a
    per-patient distant-metastasis frequency in familial cohorts. A band was
    previously asserted here on a methods sentence that carried no frequency
    information; that is corrected rather than re-sourced.
  phenotype_term:
    preferred_term: Neoplasm of the lung
    term:
      id: HP:0100526
      label: Neoplasm of the lung
  evidence:
  - reference: PMID:40908394
    reference_title: "Relationship between affected family members and clinical aggressiveness in Familial non-medullary thyroid carcinoma: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "distant metastasis (OR: 2.43 and 3.93)"
    explanation: >-
      Pooled odds ratios for distant metastasis in two-relative and
      three-or-more-relative familial disease versus sporadic non-medullary
      thyroid carcinoma - the largest familial effect size in this entry's
      evidence base, and a relative rather than absolute measure, which is why
      no frequency band is derived from it.
  - reference: PMID:25637073
    reference_title: "Endocrine tumours: familial nonmedullary thyroid carcinoma is a more aggressive disease: a systematic review and meta-analysis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "FNMTC patients had an increased rate of recurrence (OR=1.72, 95% CI: 1.34 to 2.20) and decreased disease-free survival (DFS) (HR=1.83, 95% CI: 1.34 to 2.52) in comparison with SNMTC patients."
    explanation: >-
      Supports the adverse-outcome dimension of which distant metastasis is the
      most severe component; PARTIAL because the pooled estimate is for
      recurrence and disease-free survival rather than for distant metastasis
      specifically.
- category: Systemic
  name: Earlier Age at Onset in Successive Generations
  description: >-
    Second-generation affected family members present at an earlier age and with
    more advanced disease than the first generation, a pattern described as
    clinical anticipation. Whether this reflects a biological anticipation
    mechanism or ascertainment plus intensified surveillance of known families is
    unresolved; no repeat-expansion mechanism has been demonstrated. The
    interpretation is tracked as the ALTERNATIVE `clinical_anticipation`
    hypothesis group, never as a canonical mechanism.
  notes: >-
    Deliberately left without a `phenotype_term`. HPO's only anticipation
    concept, HP:0003743 "Genetic anticipation", is NOT a phenotypic
    abnormality: `runoak -i sqlite:obo:hp ancestors -p i HP:0003743` returns
    only HP:0000001, HP:0000005 (Mode of inheritance) and HP:0034335
    (Inheritance qualifier), so it is not reachable from HP:0000118 and cannot
    validate against the PhenotypeTerm dynamic enum, whose source nodes are
    HP:0000118 and MONDO:0000001. Its definition ("A type of autosomal dominant
    inheritance involving a gene that exhibits anticipation...") also asserts an
    inheritance mechanism, which would over-commit this entry to the ALTERNATIVE
    anticipation hypothesis rather than merely recording the observation. The
    previous binding to HP:0100031 "Neoplasm of the thyroid gland" was a genuine
    term-claim mismatch and has been removed rather than replaced. An NTR for a
    phenotypic-abnormality term expressing "earlier age at onset in successive
    generations" would be the clean resolution.
  evidence:
  - reference: PMID:18832444
    reference_title: Familial non-medullary thyroid carcinoma displays the features of clinical anticipation suggestive of a distinct biological entity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among 47 FNMTC with parent-child relationship, we found an earlier age at disease presentation (P<0.0001), diagnosis (P<0.0001), and disease onset (P=0.04) in the second generation when compared with the first generation."
    explanation: Primary quantitative evidence for earlier onset in the second generation.
  - reference: PMID:26191611
    reference_title: Clinicopathological features and prognosis of familial papillary thyroid carcinoma--a large-scale, matched, case-control study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The presence of familial history in PTC indicates an increase in biological aggressiveness, and patients in the second generation may exhibit the 'genetic anticipation' phenomenon."
    explanation: Independent matched case-control replication of the anticipation observation.
- category: Neoplasm
  name: Hurthle Cell Thyroid Adenoma
  subtype: TCO
  description: >-
    Oxyphilic (Hurthle-cell / oncocytic) change in both benign and malignant
    thyroid tumours is the defining histologic signature of the TCO (19p13.2)
    subtype and is not a general feature of FNMTC.
  phenotype_term:
    preferred_term: Hurthle cell thyroid adenoma
    term:
      id: HP:0006781
      label: Hurthle cell thyroid adenoma
  evidence:
  - reference: PMID:9837827
    reference_title: A gene predisposing to familial thyroid tumors with cell oxyphilia maps to chromosome 19p13.2.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC."
    explanation: >-
      Establishes oxyphilic change in the benign as well as the malignant
      tumours of the TCO kindred, which is what binds this descriptor to the
      adenoma rather than the carcinoma term.
- category: Neoplasm
  name: Papillary Renal Neoplasia
  subtype: fPTC-PRN
  description: >-
    Papillary renal neoplasia occurring together with papillary thyroid
    carcinoma and nodular thyroid disease defines the fPTC/PRN (1q21) subtype.
    It is a subtype-restricted feature, not a feature of FNMTC generally, and is
    the extra-thyroidal finding that should prompt renal imaging in such a
    kindred.
  phenotype_term:
    preferred_term: Papillary renal cell carcinoma
    term:
      id: HP:0006766
      label: Papillary renal cell carcinoma
  evidence:
  - reference: PMID:10843148
    reference_title: "Papillary thyroid carcinoma associated with papillary renal neoplasia: genetic linkage analysis of a distinct heritable tumor syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In addition to the known association of fPTC with nodular thyroid disease, we observed the otherwise rare entity of papillary renal neoplasia (PRN) in two kindred members, one affected with PTC and the other an obligate carrier."
    explanation: >-
      Documents papillary renal neoplasia in the index fPTC/PRN kindred,
      including in an obligate carrier.
- category: Systemic
  name: Hashimoto Thyroiditis
  description: >-
    Coexisting Hashimoto thyroiditis was reported more frequently in the second
    generation of familial papillary thyroid carcinoma kindreds than in the
    first in a large matched case-control study, suggesting an autoimmune
    thyroid component in some families. No frequency band is asserted - the
    cited study reports a between-generation contrast rather than a prevalence.
  phenotype_term:
    preferred_term: Hashimoto thyroiditis
    term:
      id: HP:0000872
      label: Hashimoto thyroiditis
  evidence:
  - reference: PMID:26191611
    reference_title: Clinicopathological features and prognosis of familial papillary thyroid carcinoma--a large-scale, matched, case-control study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patients with FPTC in the second generation showed an earlier age of onset, more frequent Hashimoto's thyroiditis and a higher recurrence rate than the first generation"
    explanation: Reports excess Hashimoto thyroiditis in second-generation familial papillary thyroid carcinoma.
histopathology:
- name: Multifocality
  description: >-
    More than one discrete tumour focus within the thyroid, frequently
    bilateral. Reported at higher frequency in familial than in matched sporadic
    disease in independent meta-analyses and is the histopathologic correlate of
    the field-predisposition model.
  frequency: FREQUENT
  notes: >-
    No finding_term is bound. NCIT has no generic "multifocal" morphologic
    finding reachable from the HistopathologyFindingTerm roots - NCIT:C25253
    (Multifocal) is a general qualifier, NCIT:C36180 (Multifocal Lesion) sits
    under Finding / Lesion by Focality, and the reachable multifocal terms are
    all organ-specific tumour classes. Left deliberately unbound rather than
    mis-bound; a candidate NCIT gap.
  evidence:
  - reference: PMID:25637073
    reference_title: "Endocrine tumours: familial nonmedullary thyroid carcinoma is a more aggressive disease: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "higher risk of multifocal (OR=1.50, 95% CI: 1.32 to 1.71), bilateral (OR=1.29, 95% CI: 1.00 to 1.66)"
    explanation: Pooled odds ratios for multifocality and bilaterality across 12 studies.
- name: Oxyphilic (Hurthle) Cell Change
  subtype: TCO
  description: >-
    Oncocytic / oxyphilic cytoplasmic change affecting both benign and malignant
    thyroid tumours within the same kindred. Diagnostic of the TCO (19p13.2)
    subtype rather than of FNMTC generally.
  diagnostic: true
  notes: >-
    No finding_term is bound. The reachable NCIT candidates (NCIT:C7072
    Oncocytic Neoplasm, NCIT:C3759 Oncocytic Adenoma) are neoplasm classes
    rather than the cytologic change being described, and NCIT:C35567 Hurthle
    Cell Metaplasia is a retired concept. Left deliberately unbound rather than
    mis-bound, consistent with the Multifocality entry above; a candidate NCIT
    gap.
  evidence:
  - reference: PMID:9837827
    reference_title: A gene predisposing to familial thyroid tumors with cell oxyphilia maps to chromosome 19p13.2.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC."
    explanation: Defines the oxyphilic histopathologic signature of the TCO subtype.
genetic:
- name: FOXE1
  association: Susceptibility - best-replicated locus (9q22.33), common risk allele plus rare segregating variants
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  gene_term:
    preferred_term: FOXE1
    term:
      id: hgnc:3806
      label: FOXE1
  variants:
  - name: rs965513
    description: Common 9q22.33 risk allele nearest to FOXE1, the most consistently replicated thyroid cancer GWAS signal.
  - name: p.A248G
    description: Rare germline FOXE1 missense variant (c.743C>G) segregating with disease in one FNMTC family.
  evidence:
  - reference: PMID:19198613
    reference_title: Common variants on 9q22.33 and 14q13.3 predispose to thyroid cancer in European populations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Overall, the strongest association signals were observed for rs965513 on 9q22.33 (OR = 1.75; P = 1.7 x 10(-27)) and rs944289 on 14q13.3 (OR = 1.37; P = 2.0 x 10(-9))."
    explanation: Genome-wide association evidence for the FOXE1-proximal 9q22.33 common risk allele, the most consistently replicated thyroid cancer susceptibility signal.
  - reference: PMID:19198613
    reference_title: Common variants on 9q22.33 and 14q13.3 predispose to thyroid cancer in European populations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The gene nearest to the 9q22.33 locus is FOXE1 (TTF2) and NKX2-1 (TTF1) is among the genes located at the 14q13.3 locus. Both variants contribute to an increased risk of both papillary and follicular thyroid cancer."
    explanation: Assigns the 9q22.33 and 14q13.3 signals to FOXE1 and NKX2-1 respectively, for both papillary and follicular histology.
  - reference: PMID:25381600
    reference_title: Identification of a novel germline FOXE1 variant in patients with familial non-medullary thyroid carcinoma (FNMTC).
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This study represents the first evidence of involvement of a germline FOXE1 rare variant in FNMTC etiology and suggests that mutations in MAPK pathway-related genes may contribute to tumor development in these familial cases."
    explanation: Extends FOXE1 from a common-variant risk locus to a rare germline variant segregating in an FNMTC family.
- name: NKX2-1 (TITF-1)
  association: Susceptibility - 14q13.3 common risk allele plus the germline A339V variant in MNG/PTC families
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  gene_term:
    preferred_term: NKX2-1
    term:
      id: hgnc:11825
      label: NKX2-1
  variants:
  - name: p.A339V
    description: Germline NKX2-1/TITF-1 missense variant (c.1016C>T) found in 4 of 20 patients with multinodular goiter plus papillary thyroid carcinoma.
  - name: rs944289
    description: Common 14q13.3 risk allele near NKX2-1.
  evidence:
  - reference: PMID:19176457
    reference_title: A germline mutation (A339V) in thyroid transcription factor-1 (TITF-1/NKX2.1) in patients with multinodular goiter and papillary thyroid carcinoma.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A missense mutation (1016C>T) was identified in TITF-1/NKX2.1 that led to a mutant TTF-1 protein (A339V) in four of the 20 MNG/PTC patients (20%)."
    explanation: Identifies the recurrent germline NKX2-1 variant in patients with multinodular goiter and papillary carcinoma.
  - reference: PMID:19176457
    reference_title: A germline mutation (A339V) in thyroid transcription factor-1 (TITF-1/NKX2.1) in patients with multinodular goiter and papillary thyroid carcinoma.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Notably, this germline mutation was dominantly inherited in two families, with some members bearing the mutation affected with MNG, associated with either PTC or colon cancer."
    explanation: Demonstrates dominant familial transmission of the A339V allele.
- name: SRGAP1
  association: Susceptibility - low-penetrance / possible modifier gene at 12q14
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  gene_term:
    preferred_term: SRGAP1
    term:
      id: hgnc:17382
      label: SRGAP1
  variants:
  - name: p.Q149H
    description: SRGAP1 Fes/CIP4 homology domain missense variant segregating in one family; severely impairs CDC42 inactivation.
  - name: p.A275T
    description: SRGAP1 Fes/CIP4 homology domain missense variant segregating in one family.
  - name: p.R617C
    description: SRGAP1 RhoGAP domain missense variant; severely impairs CDC42 inactivation.
  evidence:
  - reference: PMID:23539728
    reference_title: SRGAP1 is a candidate gene for papillary thyroid carcinoma susceptibility.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Linkage analysis and association studies identified the Slit-Robo Rho GTPase activating protein 1 gene (SRGAP1) in the linkage peak as a candidate gene."
    explanation: Genome-wide linkage in 38 families plus association testing nominated SRGAP1.
  - reference: PMID:23539728
    reference_title: SRGAP1 is a candidate gene for papillary thyroid carcinoma susceptibility.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Our findings suggest that SRGAP1 is a candidate gene in PTC susceptibility. SRGAP1 is likely a low-penetrant gene, possibly of a modifier type."
    explanation: The authors themselves classify SRGAP1 as a candidate low-penetrance/modifier gene rather than an established cause.
  - reference: PMID:27530615
    reference_title: HABP2 germline variants are uncommon in familial nonmedullary thyroid cancer.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "From whole exome data, pathogenic mutations were not identified in HABP2, SRGAP1, NKX2-1, SRRM2 or FOXE1."
    explanation: Exome sequencing of 59 participants from 20 independent Australian FNMTC kindreds found no pathogenic SRGAP1 variants, arguing against a general role.
- name: SRRM2
  association: Susceptibility - single-family splicing-factor candidate, not replicated in other kindreds
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  gene_term:
    preferred_term: SRRM2
    term:
      id: hgnc:16639
      label: SRRM2
  variants:
  - name: p.S346F
    description: SRRM2 missense variant (c.1037C>T, rs149019598) cosegregating with papillary thyroid carcinoma in a single six-case family.
  evidence:
  - reference: PMID:26135620
    reference_title: A germline mutation in SRRM2, a splicing factor gene, is implicated in papillary thyroid carcinoma predisposition.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "This heterozygous variant, c.1037C > T (Ser346Phe or S346F; rs149019598) cosegregated with PTC in the family. It was not found in 138 other PTC families."
    explanation: >-
      Cosegregation in one six-case family supports the variant, but its absence
      from 138 further PTC families shows it does not generalize, so support for a
      disease-wide role is partial.
- name: HABP2
  association: Disputed - the p.G534E variant was proposed as a dominant susceptibility allele but failed replication and is common in the general population
  relationship_type: DISPUTED
  variant_origin: GERMLINE
  gene_term:
    preferred_term: HABP2
    term:
      id: hgnc:4798
      label: HABP2
  variants:
  - name: p.G534E
    description: >-
      HABP2 c.1601G>A (p.G534E, rs7080536) at 10q25.3, within the serine
      protease trypsin domain, originally proposed as an FNMTC susceptibility
      allele; present in 7-9% of unselected populations and failing
      cosegregation in independent kindreds.
    type: MISSENSE
    clinical_significance: BENIGN
    gene:
      preferred_term: HABP2
      term:
        id: hgnc:4798
        label: HABP2
    evidence:
    - reference: PMID:27530615
      reference_title: HABP2 germline variants are uncommon in familial nonmedullary thyroid cancer.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The G534E variant in HABP2 does not account for the familial nature of NMTC in Australian kindreds, and is common in the general population."
      explanation: >-
        Supports the BENIGN classification - a variant this common in the
        general population that fails to explain familial disease cannot be a
        penetrant predisposition allele.
    - reference: PMID:26745718
      reference_title: HABP2 G534E Variant in Papillary Thyroid Carcinoma.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The variant was found to be present in 6.1% familial cases, 8.0% sporadic cases (2 individuals were homozygous for the variant) and 8.7% controls."
      explanation: >-
        Independent case-control frequencies, including homozygotes among
        sporadic cases, corroborating the BENIGN classification.
  notes: >-
    This is the most instructive controversy in FNMTC genetics and is curated with
    both the original report and its refutations. The 2015 report of germline
    HABP2 p.G534E in an FNMTC kindred was rapidly followed by multiple independent
    studies that failed to reproduce cosegregation and found the allele at 7-9%
    frequency in unselected populations - far too common for a highly penetrant
    dominant cancer allele. HABP2 p.G534E should not be treated as a pathogenic
    FNMTC variant or used for predictive testing of relatives.
  evidence:
  - reference: PMID:26222560
    reference_title: Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here, we report a germline variant of HABP2 in seven affected members of a kindred with familial nonmedullary thyroid cancer and in 4.7% of 423 patients with thyroid cancer."
    explanation: The original report proposing germline HABP2 as an FNMTC susceptibility gene.
  - reference: PMID:26222560
    reference_title: Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Functional studies showed that HABP2 has a tumor-suppressive effect, whereas the G534E variant results in loss of function."
    explanation: The functional argument offered in support of the original claim.
  - reference: PMID:27530615
    reference_title: HABP2 germline variants are uncommon in familial nonmedullary thyroid cancer.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Heterozygosity for the G534E variant in HABP2 was found in 1 of 37 probands (2.7 %), but did not cosegregate with disease in this kindred, being absent in the proband's affected sister."
    explanation: Direct refutation - the variant failed to cosegregate with disease in the one kindred in which it was found.
  - reference: PMID:27530615
    reference_title: HABP2 germline variants are uncommon in familial nonmedullary thyroid cancer.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Heterozygosity for the G534E variant in HABP2 was present in 7.6 % of Busselton Health Study participants (N = 4634, unknown disease status) and 9.3 % of TwinsUK participants (N = 1195, no history of thyroid cancer)."
    explanation: Population-frequency refutation - the allele is far too common to be a highly penetrant dominant cancer-predisposing variant.
  - reference: PMID:27530615
    reference_title: HABP2 germline variants are uncommon in familial nonmedullary thyroid cancer.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "The G534E variant in HABP2 does not account for the familial nature of NMTC in Australian kindreds, and is common in the general population."
    explanation: The authors' explicit conclusion rejecting HABP2 p.G534E as the explanation for FNMTC.
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Our families are negative for variants reported as likely causative, namely those lying in the HABP2, MAP2K5 and DUOX2 genes."
    explanation: Independent Italian series of 33 unrelated FNMTC families is negative for the HABP2 variant, further refuting a general role.
  - reference: PMID:26832773
    reference_title: HABP2 G534E Mutation in Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These results are consistent with HABP2 G534E being a susceptibility gene in a subgroup of FNMTC, providing important diagnostic implications for this hereditary thyroid cancer."
    explanation: >-
      The one substantial independent report favouring a susceptibility role,
      carried so the DISPUTED typing rests on both sides of the literature.
  - reference: PMID:26745718
    reference_title: HABP2 G534E Variant in Papillary Thyroid Carcinoma.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "The variant did not segregate with PTC in one large and 6 smaller families in which it occurred."
    explanation: Segregation failure across seven independent carrier families.
  - reference: PMID:26745718
    reference_title: HABP2 G534E Variant in Papillary Thyroid Carcinoma.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "In keeping with data from the literature and databases the expression of HABP2 was highest in the liver, much lower in 3 other tested tissues (breast, kidney, brain) but not found in thyroid."
    explanation: >-
      Absence of HABP2 expression in thyroid is an independent biological
      argument against a thyroid-autonomous tumour-suppressor role.
  - reference: PMID:26906432
    reference_title: HABP2 Gene Mutations Do Not Cause Familial or Sporadic Non-Medullary Thyroid Cancer in a Highly Inbred Middle Eastern Population.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "None of the familial NMTC carried HABP2 mutations. Of 509 sporadic NMTC, only one case (0.2%) harbored the G534E variant."
    explanation: >-
      Non-replication in a large, highly consanguineous Middle Eastern series,
      extending the refutation beyond European and Australian cohorts.
- name: NID1
  association: Candidate only - single-family whole-exome finding awaiting replication
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  gene_term:
    preferred_term: NID1
    term:
      id: hgnc:7821
      label: NID1
  variants:
  - name: p.Ile657Met
    description: >-
      NID1 c.1971T>G (p.Ile657Met), the only variant cosegregating with
      papillary thyroid carcinoma across three generations of a Brazilian
      family; very rare in population databases.
  notes: >-
    Candidate-level only. The authors themselves state that replication is
    required before NID1 can be accepted as a predisposition gene, so treat
    p.Ile657Met as a variant of uncertain significance and do not use it for
    predictive testing. Included because it is one of the few post-2020
    whole-exome candidates with clean multi-generation cosegregation, and
    because tracking such candidates explicitly is how the HABP2 episode is
    avoided a second time.
  evidence:
  - reference: PMID:34941562
    reference_title: Identification of NID1 as a novel candidate susceptibility gene for familial non-medullary thyroid carcinoma using whole-exome sequencing.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "The missense variant p.Ile657Met in the NID1 gene was the only variant that co-segregated with the disease, while absent in unaffected family members and controls."
    explanation: >-
      The cosegregation finding in the single index family; PARTIAL because no
      independent replication exists and the authors explicitly call for it.
- name: MAP2K5
  association: Disputed - reported candidate not confirmed in independent FNMTC series
  relationship_type: DISPUTED
  variant_origin: GERMLINE
  gene_term:
    preferred_term: MAP2K5
    term:
      id: hgnc:6845
      label: MAP2K5
  evidence:
  - reference: PMID:38571492
    reference_title: Chromosomal localization of mutated genes in non-syndromic familial thyroid cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Subsequent research employed more advanced techniques such as Genome-wide Association Study and Whole Exome Sequencing, leading to the discovery of genes such as IMMP2L, GALNTL4, WDR11-AS1, DUOX2, NOP53, MAP2K5, and others."
    explanation: Records MAP2K5 among the sequencing-era candidate genes reported for non-syndromic FNMTC.
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Our families are negative for variants reported as likely causative, namely those lying in the HABP2, MAP2K5 and DUOX2 genes."
    explanation: An independent series of 33 FNMTC families carried no reported MAP2K5 variant, arguing against a general causal role.
- name: DUOX2
  association: Disputed - single-family candidate variant absent from an independent validation series
  relationship_type: DISPUTED
  variant_origin: GERMLINE
  gene_term:
    preferred_term: DUOX2
    term:
      id: hgnc:13273
      label: DUOX2
  variants:
  - name: p.Y1203H
    description: DUOX2 missense variant (c.3607A>G) reported to cosegregate in one FNMTC family; absent from 86 members of 33 independent Italian families.
  evidence:
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Unfortunately, the DUOX2 p.Y1203H variant was not found in either the 74 affected or the 12 not affected family members of our series."
    explanation: Explicit failed validation of the DUOX2 candidate variant in 86 members of 33 independent FNMTC families.
- name: APC
  association: Causative for the syndromic form - familial adenomatous polyposis / Gardner syndrome with cribriform-morular thyroid carcinoma
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: APC
    term:
      id: hgnc:583
      label: APC
  notes: >-
    A germline APC variant places the patient in the syndromic category and, by
    the conventional definition, outside non-syndromic FNMTC. See the
    Classic Familial Adenomatous Polyposis entry; that content is not duplicated
    here.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Out of all FNMTC cases, only 5% in the syndromic form has well-studied driver germline mutations. These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Establishes familial adenomatous polyposis / Gardner syndrome as one of the well-characterized syndromic causes to be excluded.
  - reference: PMID:24093640
    reference_title: "Thyroid cancer complicating familial adenomatous polyposis: mutation spectrum of at-risk individuals."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lifetime risk of thyroid cancer associated with FAP has been reported as 1-2%. The mean age at diagnosis of thyroid carcinoma in FAP has been reported at 28 years."
    explanation: >-
      Quantifies the magnitude and age profile of APC-associated thyroid cancer
      risk, which is what makes recognizing FAP actionable in a young FNMTC-like
      proband.
  - reference: PMID:24093640
    reference_title: "Thyroid cancer complicating familial adenomatous polyposis: mutation spectrum of at-risk individuals."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "There is increased risk for thyroid cancer in individuals with APC mutations at the 5' end (proximal to codon 528) along with the established high risk group harboring mutation at codon 1061."
    explanation: Gives the APC genotype-to-thyroid-phenotype correlation within FAP.
  - reference: PMID:28490611
    reference_title: Extracolonic cancer risk in Dutch patients with APC (adenomatous polyposis coli)-associated polyposis.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Thyroid cancer was observed in only 1.5% of the cases."
    explanation: >-
      Independent registry cohort giving a concordant but deliberately deflating
      figure; PARTIAL because the authors frame thyroid cancer as an uncommon
      and rarely fatal FAP manifestation.
- name: PTEN
  association: Causative for the syndromic form - Cowden syndrome / PTEN hamartoma tumor syndrome
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: PTEN
    term:
      id: hgnc:9588
      label: PTEN
  notes: >-
    See the Cowden Syndrome and PTEN Hamartoma Tumor Syndrome entries, which
    already curate non-medullary thyroid carcinoma as a component phenotype.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Establishes Cowden syndrome as a syndromic cause of familial non-medullary thyroid carcinoma.
  - reference: PMID:22252256
    reference_title: Lifetime cancer risks in individuals with germline PTEN mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "thyroid (51.1, 38.1-67.1)"
    explanation: >-
      Standardised incidence ratio of 51.1 (95% CI 38.1-67.1) for thyroid cancer
      in a prospective cohort of 3,399 individuals of whom 368 carried
      deleterious germline PTEN mutations - among the highest component-cancer
      risks in PHTS and the quantitative reason PTEN testing is actionable.
  - reference: PMID:22252256
    reference_title: Lifetime cancer risks in individuals with germline PTEN mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A series of 3,399 individuals meeting relaxed International Cowden Consortium PHTS criteria were prospectively recruited; 368 individuals were found to have deleterious germline PTEN mutations."
    explanation: Establishes the prospective PHTS cohort from which the thyroid SIR is derived.
- name: PRKAR1A
  association: Causative for the syndromic form - Carney complex type 1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: PRKAR1A
    term:
      id: hgnc:9388
      label: PRKAR1A
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Establishes Carney complex type 1 as a syndromic cause to be excluded before diagnosing non-syndromic FNMTC.
  - reference: PMID:16756677
    reference_title: Carney complex (CNC).
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most common endocrine gland manifestations are acromegaly, thyroid and testicular tumors, and adrenocorticotropic hormone (ACTH)-independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD)."
    explanation: >-
      Places thyroid tumours among the core endocrine manifestations of Carney
      complex, which is what makes the syndrome relevant to an FNMTC-like
      pedigree.
  - reference: PMID:16756677
    reference_title: Carney complex (CNC).
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Heterozygous inactivating mutations of PRKAR1A were reported initially in 45 to 65% of CNC index cases, and may be present in about 80% of the CNC families presenting mainly with Cushing's syndrome."
    explanation: >-
      Gives the PRKAR1A mutation detection rate, i.e. the expected yield of
      targeted testing when Carney complex is suspected.
- name: WRN
  association: Causative for the syndromic form - Werner syndrome
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: WRN
    term:
      id: hgnc:12791
      label: WRN
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Establishes Werner syndrome as a syndromic cause to be excluded.
  - reference: PMID:23573208
    reference_title: "Spectrum and risk of neoplasia in Werner syndrome: a systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Werner syndrome (WS) is an autosomal recessive genetic instability and progeroid ('premature aging') syndrome which is associated with an elevated risk of cancer."
    explanation: >-
      Establishes the autosomal recessive, genomic-instability mechanism - WRN
      is the only recessive member of the syndromic set, which matters when
      interpreting a pedigree that lacks vertical transmission.
  - reference: PMID:23573208
    reference_title: "Spectrum and risk of neoplasia in Werner syndrome: a systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cancer risk defined by SIRs was significantly elevated in Japan-resident WS patients for the six most frequent neoplasms except leukemia, ranging from 53.5-fold for melanoma of the skin (95% CI: 24.5, 101.6) to 8.9 (95% CI: 4.9, 15.0) for thyroid neoplasms."
    explanation: Quantifies the thyroid-neoplasm standardised incidence ratio (8.9) in Werner syndrome.
- name: DICER1
  association: Causative for the syndromic form - DICER1 tumor predisposition syndrome
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: DICER1
    term:
      id: hgnc:17098
      label: DICER1
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Establishes DICER1 syndrome as a syndromic cause to be excluded.
  - reference: PMID:24761742
    reference_title: DICER1-Related Tumor Predisposition.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most common features are lung cysts and thyroid nodules."
    explanation: >-
      GeneReviews statement placing thyroid nodules among the two commonest
      DICER1 features - the reason a childhood-onset nodular thyroid pedigree
      should prompt DICER1 testing rather than an FNMTC label.
  - reference: PMID:24761742
    reference_title: DICER1-Related Tumor Predisposition.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "DICER1-related neoplasms include pleuropulmonary blastoma (PPB), Sertoli-Leydig cell tumor (SLCT), including gynandroblastoma, pediatric cystic nephroma (CN), and differentiated thyroid carcinoma."
    explanation: Confirms differentiated thyroid carcinoma as part of the DICER1 tumour spectrum.
- name: POT1
  subtype: Long Telomere Syndrome PTC
  association: >-
    Germline pathogenic POT1 variants produce ultra-long telomeres and, together
    with TINF2 and ACD, define a recently delineated long-telomere syndromic
    papillary thyroid cancer subtype found in 4.5% of familial and 1.5% of
    unselected cases. Note the direction of effect - this is telomere
    LENGTHENING, the mirror image of the telomere-shortening/fragility model.
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  gene_term:
    preferred_term: POT1
    term:
      id: hgnc:17284
      label: POT1
  evidence:
  - reference: PMID:38688277
    reference_title: Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD."
    explanation: Identifies POT1 among the three shelterin predisposition genes.
  - reference: PMID:38688277
    reference_title: Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "They were found in 4.5% and 1.5% of familial and unselected cases, respectively."
    explanation: Quantifies the shelterin contribution to familial papillary thyroid cancer.
- name: TINF2
  subtype: Long Telomere Syndrome PTC
  association: >-
    Germline pathogenic TINF2 variants contribute to the long-telomere papillary
    thyroid cancer subtype.
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  gene_term:
    preferred_term: TINF2
    term:
      id: hgnc:11824
      label: TINF2
  evidence:
  - reference: PMID:38688277
    reference_title: Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD."
    explanation: Identifies TINF2 among the three shelterin predisposition genes.
- name: ACD
  subtype: Long Telomere Syndrome PTC
  association: >-
    Germline pathogenic ACD (TPP1) variants contribute to the long-telomere
    papillary thyroid cancer subtype.
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  gene_term:
    preferred_term: ACD
    term:
      id: hgnc:25070
      label: ACD
  evidence:
  - reference: PMID:38688277
    reference_title: Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD."
    explanation: Identifies ACD among the three shelterin predisposition genes.
has_subtypes:
- name: Non-Syndromic FNMTC
  display_name: Non-Syndromic (Isolated) Familial Non-Medullary Thyroid Carcinoma
  description: >-
    The default form and the main subject of this entry - follicular-cell thyroid
    cancer in two or more first-degree relatives with no recognised
    tumour-predisposition syndrome and no identified environmental cause. No
    validated major susceptibility gene exists and the working model is
    polygenic. The subtypes below are the named linkage loci and the one
    molecularly defined subset carved out of this group; the recognised
    syndromic causes are modelled as differential diagnoses rather than
    subtypes, per this entry's scoping decision - with the single principled
    exception of the long-telomere shelterin subtype, which is syndromic in
    tumour spectrum but is not recognisable before testing and was carved
    directly out of non-syndromic-ascertained cohorts. No `subtype_term` is
    bound on this root subtype: the entry's own `disease_term`, MONDO:0017896,
    is itself defined as the non-syndromic form, so binding the same term here
    would be circular rather than informative.
  evidence:
  - reference: PMID:26222560
    reference_title: Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nonsyndromic familial nonmedullary thyroid cancer accounts for more than 95% of all cases of familial nonmedullary thyroid cancer."
    explanation: Establishes the non-syndromic form as the numerically dominant one.
- name: TCO
  display_name: TCO - Thyroid Tumours with Cell Oxyphilia (19p13.2)
  description: >-
    A non-syndromic FNMTC entity defined in a French pedigree with multinodular
    goitre and non-medullary thyroid carcinoma in which both benign and malignant
    thyroid tumours show oxyphilic (Hurthle/oncocytic) cell change. Mapped by
    linkage to 19p13.2 and named TCO; the causal gene has not been identified.
  subtype_term:
    preferred_term: thyroid carcinoma, nonmedullary, with or without cell oxyphilia
    term:
      id: MONDO:0011312
      label: thyroid carcinoma, nonmedullary, with or without cell oxyphilia
  evidence:
  - reference: PMID:9837827
    reference_title: A gene predisposing to familial thyroid tumors with cell oxyphilia maps to chromosome 19p13.2.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "TCO was mapped to chromosome 19p13.2 by linkage analysis with a whole-genome panel of microsatellite markers."
    explanation: Establishes the TCO locus assignment.
  - reference: PMID:9837827
    reference_title: A gene predisposing to familial thyroid tumors with cell oxyphilia maps to chromosome 19p13.2.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC."
    explanation: Defines the oxyphilic histologic signature distinguishing this subtype.
- name: fPTC-PRN
  display_name: fPTC/PRN - Familial Papillary Thyroid Carcinoma with Papillary Renal Neoplasia (1q21)
  description: >-
    A distinct heritable tumour syndrome characterised by the familial
    association of papillary thyroid carcinoma, nodular thyroid disease and
    papillary renal neoplasia, mapped by linkage to 1q21 in a large
    three-generation kindred. MET, the gene of isolated familial papillary renal
    neoplasia, was excluded by both linkage and sequencing.
  subtype_term:
    preferred_term: familial papillary thyroid carcinoma with renal papillary neoplasia
    term:
      id: MONDO:0011578
      label: familial papillary thyroid carcinoma with renal papillary neoplasia
  evidence:
  - reference: PMID:10843148
    reference_title: "Papillary thyroid carcinoma associated with papillary renal neoplasia: genetic linkage analysis of a distinct heritable tumor syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A distinct inherited tumor syndrome has been characterized as the familial association of papillary thyroid cancer, nodular thyroid disease, and papillary renal neoplasia."
    explanation: Defines the fPTC/PRN phenotype.
  - reference: PMID:10843148
    reference_title: "Papillary thyroid carcinoma associated with papillary renal neoplasia: genetic linkage analysis of a distinct heritable tumor syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A genome-wide screening and an investigation of specific candidate genes demonstrated that the fPTC/PRN phenotype was linked to 1q21."
    explanation: Establishes the 1q21 locus assignment.
- name: NMTC1
  display_name: NMTC1 - Familial Non-Medullary Thyroid Carcinoma Susceptibility Locus (2q21)
  description: >-
    A susceptibility locus mapped to 2q21, first through a shared haplotype in a
    large Tasmanian papillary thyroid carcinoma pedigree and then replicated by
    linkage in 80 independent pedigrees. The signal strengthened markedly when
    pedigrees were stratified for the follicular variant of papillary thyroid
    carcinoma, suggesting NMTC1 predisposes specifically to follicular-patterned
    tumours. The causal gene has not been identified.
  subtype_term:
    preferred_term: thyroid cancer, nonmedullary, 1
    term:
      id: MONDO:0008567
      label: thyroid cancer, nonmedullary, 1
  evidence:
  - reference: PMID:11438887
    reference_title: Localization of a susceptibility gene for familial nonmedullary thyroid carcinoma to chromosome 2q21.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These results indicate the existence of a susceptibility locus for familial NMTC on chromosome 2q21."
    explanation: Establishes the NMTC1 locus assignment.
  - reference: PMID:11438887
    reference_title: Localization of a susceptibility gene for familial nonmedullary thyroid carcinoma to chromosome 2q21.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Stratification based on the presence of at least one case of the follicular variant of PTC, the phenotype observed in the Tas1 family, identified 17 such pedigrees, yielding a maximal HLOD score of 4.17 (alpha=0.80) and NPL=4.99 (P=.00002) at markers AFMa272zg9 and D2S2271, respectively."
    explanation: Documents the follicular-variant stratification that sharpens the 2q21 signal.
- name: Long Telomere Syndrome PTC
  display_name: Telomere-Lengthening (POT1/TINF2/ACD) Syndromic Papillary Thyroid Cancer
  description: >-
    The one molecularly defined subset so far carved out of non-syndromic FNMTC -
    germline shelterin (POT1, TINF2, ACD) variants producing ultra-long telomeres
    and predisposing to papillary thyroid cancer alongside melanoma, lymphoma and
    sarcoma. Found in 4.5% of familial cases, and in 22% of individuals with both
    papillary thyroid cancer and melanoma, which makes the combination clinically
    recognisable. Directionally opposite to the telomere-shortening/fragility
    model in the pathograph above; both are curated so the tension is visible,
    and both are now separable at the pathograph level under the
    `telomere_length_predisposition` hypothesis group rather than only in prose.
    Note the apparent tension with the scoping rule stated on Non-Syndromic
    FNMTC: this subtype IS syndromic in its tumour spectrum, but unlike FAP,
    Cowden, Carney, Werner and DICER1 it is not recognisable before testing and
    was carved directly out of cohorts ascertained as non-syndromic FNMTC, so it
    belongs here as a subtype rather than as a differential. No `subtype_term`
    is bound: MONDO has no generic term for the long-telomere / shelterin
    papillary thyroid cancer syndrome, only gene-specific terms (e.g.
    MONDO:0100570 for POT1 tumour predisposition) that would under-represent a
    three-gene entity. Left deliberately unbound rather than mis-bound; a
    candidate MONDO NTR.
  genes:
  - preferred_term: POT1
    term:
      id: hgnc:17284
      label: POT1
  - preferred_term: TINF2
    term:
      id: hgnc:11824
      label: TINF2
  - preferred_term: ACD
    term:
      id: hgnc:25070
      label: ACD
  evidence:
  - reference: PMID:38688277
    reference_title: Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among individuals with PTC and melanoma, 22% carried a deleterious germline variant, suggesting that a long telomere syndrome might be clinically recognizable."
    explanation: Gives the clinically actionable PTC-plus-melanoma recognition rule.
  - reference: PMID:38688277
    reference_title: Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals harboring these variants had ultra-long telomere length, and 15 of 18 (83%) developed other cancers, of which melanoma, lymphoma, and sarcoma were most common."
    explanation: Establishes the ultra-long-telomere phenotype and associated tumour spectrum.
prevalence:
- population: >-
    Patients with non-medullary (follicular-cell-derived) thyroid carcinoma,
    worldwide
  measure_type: UNKNOWN
  prevalence_class: RARE
  notes: >-
    FNMTC occurrence is reported in the literature as a fraction of non-medullary
    thyroid carcinoma cases, not as a population rate, and the reported fraction
    varies with the case definition (two versus three affected first-degree
    relatives): 3-9% in older reviews using the two-relative definition, 5-15% in
    recent reviews, and approximately 5% in series using a stricter definition. No
    reliable FNMTC-specific incidence or point prevalence per 100,000 has been
    established, so no rate_per_100000 is asserted here. MONDO places
    MONDO:0017896 in the `rare` subset.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Familial non-medullary thyroid cancer (FNMTC) constitutes 3-9% of all thyroid cancers."
    explanation: The lower published estimate of the FNMTC case fraction.
  - reference: PMID:35255942
    reference_title: Genetic susceptibility to hereditary non-medullary thyroid cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "With the increasing incidence of NMTC in recent years, the familial form of the disease has also become more common than previously reported, accounting for 5-15% of NMTC cases."
    explanation: The contemporary upper estimate of the FNMTC case fraction.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the familial form of the disease has also become more common than previously reported and constitutes nearly 10% of all thyroid cancers"
    explanation: Independent estimate of roughly 10% supporting the mid-range of the reported band.
- population: >-
    Familial non-medullary thyroid carcinoma kindreds (syndromic subset)
  measure_type: UNKNOWN
  prevalence_class: UNKNOWN
  notes: >-
    Within familial disease, roughly 5% of cases are syndromic (a recognized tumor
    predisposition syndrome) and the remaining ~95% are non-syndromic. This is a
    within-disease composition figure rather than a population rate.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The susceptibility chromosomal loci and genes of 95% of FNMTC cases remain to be characterized."
    explanation: Establishes the ~95% non-syndromic / ~5% syndromic split.
treatments:
- name: Thyroidectomy
  description: >-
    Surgery is the definitive treatment and follows standard differentiated
    thyroid-cancer risk stratification - lobectomy or total thyroidectomy according
    to tumor size, multifocality and bilaterality, nodal disease and patient
    preference. Because familial tumors are more often multicentric and bilateral,
    total thyroidectomy is used frequently in referral series, but current guidance
    does not mandate a more aggressive operation on the basis of family history
    alone.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Thyroidectomy
    term:
      id: NCIT:C51648
      label: Thyroidectomy
  target_mechanisms:
  - target: Multifocal Follicular Cell Transformation
    treatment_effect: INHIBITS
    description: >-
      Removing both lobes eliminates the multicentric and contralateral disease
      that field predisposition produces, which is the mechanistic rationale for
      favouring total over partial thyroidectomy in familial kindreds.
  evidence:
  - reference: PMID:26191611
    reference_title: Clinicopathological features and prognosis of familial papillary thyroid carcinoma--a large-scale, matched, case-control study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At present, the available data are not sufficient to support a more aggressive approach for FPTC."
    explanation: Directly supports the statement that family history alone does not justify escalating the initial operation.
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Despite the more aggressive presentation of familial cases, an appropriate treatment leads to an outcome similar to that observed for sporadic cases."
    explanation: Supports treating FNMTC by standard differentiated thyroid-cancer principles rather than a familial-specific escalation.
  - reference: PMID:40392709
    reference_title: Comparison of Progression-Free Survival in Familial Non-Medullary Thyroid Cancer and Sporadic Differentiated Thyroid Cancer Patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Therefore, the management of FNMTC should align with the standard of care for DTC to avoid overtreatment of FNMTC."
    explanation: >-
      Explicit recommendation against escalating surgery on the basis of
      familial status alone, and the source of the overtreatment concern.
- name: Thyroid Lobectomy
  description: >-
    Lobectomy remains appropriate for selected small, unifocal, low-risk
    familial tumours - notably screen-detected cancers, where hemithyroidectomy
    was used in 23.5% of screen-detected FNMTC versus 0% of clinically
    presenting cases. The choice between lobectomy and total thyroidectomy
    should follow standard differentiated-thyroid-cancer risk stratification
    rather than family history alone, and is the operative counterweight to the
    reflex-total-thyroidectomy tendency in familial disease.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Thyroid Lobectomy
    term:
      id: NCIT:C51649
      label: Thyroid Lobectomy
  evidence:
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "less extensive surgery (hemithyroidectomy 23.5% vs. 0%; p = 0.002)"
    explanation: >-
      Quantifies the use of hemithyroidectomy for screen-detected, low-risk
      familial disease versus clinically presenting disease.
  - reference: PMID:26191611
    reference_title: Clinicopathological features and prognosis of familial papillary thyroid carcinoma--a large-scale, matched, case-control study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At present, the available data are not sufficient to support a more aggressive approach for FPTC."
    explanation: >-
      Supports retaining lobectomy as an option - family history alone does not
      justify mandating the more extensive operation.
- name: Cervical Lymph Node Dissection
  description: >-
    Therapeutic compartment-oriented neck dissection is performed for proven nodal
    metastasis, following standard differentiated thyroid-cancer indications.
    Familial series report higher nodal metastasis rates than sporadic disease,
    but screen-detected familial cancers have a substantially lower central-node
    metastasis rate (17.6% versus 51.1%), so nodal management should be driven
    by imaging and cytology findings rather than by familial status.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Neck Dissection
    term:
      id: NCIT:C15643
      label: Neck Dissection
  target_mechanisms:
  - target: Multifocal Follicular Cell Transformation
    treatment_effect: INHIBITS
    description: >-
      Compartment-oriented dissection removes the regional nodal disease that
      the transformed, frequently multicentric gland has seeded.
  evidence:
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a lower rate of central neck lymph node metastases (17.6% vs. 51.1%; p = 0.02)"
    explanation: >-
      Quantifies central nodal involvement in screen-detected versus clinically
      detected familial disease - the reason nodal surgery is findings-driven
      rather than familial-status-driven.
  - reference: PMID:18832444
    reference_title: Familial non-medullary thyroid carcinoma displays the features of clinical anticipation suggestive of a distinct biological entity.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "had higher rate of lymph node metastases at surgery (P=0.02) and worse outcome (P=0.04) when compared with the first generation"
    explanation: >-
      Establishes the burden of surgically confirmed nodal metastasis that neck
      dissection addresses; the abstract does not itself evaluate the operation, so
      support for the intervention is indirect.
- name: Radioactive Iodine Therapy
  description: >-
    Adjuvant radioiodine (I-131) is selected after surgery according to recurrence
    risk and radioiodine avidity, exactly as for sporadic differentiated thyroid
    cancer. Family history is not itself an indication.
  therapeutic_modality: RADIOTHERAPY
  treatment_term:
    preferred_term: Radioactive Iodine Therapy
    term:
      id: NCIT:C157968
      label: Radioactive Iodine Therapy
  evidence:
  - reference: PMID:35295987
    reference_title: "Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Given that non-syndromic familial non-medullary carcinoma and sporadic non-medullary thyroid carcinoma share the same morphology and somatic mutations, the same targeted therapies could be used at present"
    explanation: >-
      Supports applying standard sporadic differentiated thyroid-cancer treatment to
      familial disease; the quoted sentence concerns targeted therapy specifically,
      so support for the radioiodine indication is partial.
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a lower rate of radioactive iodine therapy (23.5% vs. 79%; p < 0.001) compared to those affected at enrollment."
    explanation: >-
      Shows that radioiodine use tracks disease stage at detection rather than
      familial status - screen-detected familial cancers needed it far less
      often than clinically presenting ones.
  - reference: PMID:40392709
    reference_title: Comparison of Progression-Free Survival in Familial Non-Medullary Thyroid Cancer and Sporadic Differentiated Thyroid Cancer Patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "There was no difference in radioactive iodine (RAI) therapy dosage between the groups"
    explanation: >-
      Matched-cohort evidence that administered radioiodine activity does not
      differ by familial status, supporting risk-adapted rather than
      familial-status-adapted dosing.
- name: Levothyroxine Replacement and TSH Suppression
  description: >-
    Thyroid hormone replacement is mandatory after total thyroidectomy, with
    risk-adapted TSH suppression as part of standard differentiated thyroid-cancer
    follow-up.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: levothyroxine
      term:
        id: NCIT:C62080
        label: Levothyroxine
  evidence:
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "The extensive review of the current knowledge on the genetic risk factors for non-syndromic FNMTCs underlies how the management of these tumors remains mainly clinical."
    explanation: >-
      Supports that FNMTC management is standard clinical differentiated
      thyroid-cancer care, of which post-thyroidectomy levothyroxine is a
      constituent; the abstract does not name levothyroxine, so support is partial.
- name: Kinase Inhibitor Therapy for Radioiodine-Refractory Disease
  description: >-
    Advanced radioiodine-refractory familial tumors are treated with molecularly
    selected kinase inhibition on the same rules as sporadic differentiated thyroid
    cancer - RET or NTRK inhibitors for the corresponding fusions, BRAF/MEK-directed
    therapy for BRAF-altered disease, and multikinase inhibitors otherwise - because
    the somatic driver landscape is shared.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: targeted therapy
    term:
      id: NCIT:C93352
      label: Targeted Therapy
    therapeutic_agent:
    - preferred_term: selpercatinib
      term:
        id: NCIT:C134987
        label: Selpercatinib
    - preferred_term: dabrafenib
      term:
        id: CHEBI:75045
        label: dabrafenib
    - preferred_term: lenvatinib
      term:
        id: CHEBI:85994
        label: lenvatinib
  target_mechanisms:
  - target: Acquisition of Somatic MAPK-Activating Driver Alterations
    treatment_effect: INHIBITS
    description: >-
      Kinase inhibitors act on the same somatic MAPK/RTK driver layer in familial
      tumors as in sporadic differentiated thyroid cancer.
  evidence:
  - reference: PMID:35295987
    reference_title: "Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Given that non-syndromic familial non-medullary carcinoma and sporadic non-medullary thyroid carcinoma share the same morphology and somatic mutations, the same targeted therapies could be used at present, if necessary, until more specific targeted treatments become available."
    explanation: Directly supports applying the sporadic targeted-therapy repertoire to familial tumors on the grounds of shared somatic drivers.
- name: Genetic Counseling and Family Risk Assessment
  description: >-
    Counseling covers a three-generation pedigree, recognition of syndromic
    features that would redirect testing to APC, PTEN, PRKAR1A, WRN or DICER1, and
    an explicit explanation that no validated predictive gene panel exists for
    isolated non-syndromic kindreds. Current major-society guidance does not
    recommend routine screening of first-degree relatives of patients with
    differentiated thyroid cancer, so surveillance decisions are individualized -
    with a lower threshold in families with three or more affected members,
    unusually young onset, or aggressive disease.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "For this reason, recent guidelines do not recommend screening of family members of patients with diagnosis of differentiated thyroid cancer"
    explanation: Supports the statement that routine relative screening is not currently guideline-recommended.
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is important for the clinician to recognize these phenotypes so that genetic counseling and testing can be initiated to enable surveillance for associated malignancies and genetic testing of family members."
    explanation: Supports phenotype-directed recognition of syndromic forms as the core counseling task.
diagnosis:
- name: Pedigree-Based Clinical Definition
  description: >-
    FNMTC is a clinical diagnosis of exclusion made from the pedigree: two or more
    first-degree relatives with non-medullary thyroid carcinoma, with no recognized
    tumor-predisposition syndrome and no shared predisposing environmental exposure
    (notably childhood neck irradiation). Three or more affected relatives is the
    more specific research definition, because two-case families are substantially
    contaminated by coincidental clustering of a common sporadic cancer. There is
    no diagnostic laboratory test, biomarker, or histologic feature that
    distinguishes a familial from a sporadic tumor.
  evidence:
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Familial non-medullary thyroid carcinoma (FNMTC), mainly of papillary histotype (FPTC), is defined by the presence of the disease in two or more first-degree relatives in the absence of other known familial syndromes."
    explanation: The conventional two-first-degree-relative definition, with syndrome exclusion.
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The term familial non-medullary thyroid cancers (FNMTCs) is used to indicate thyroid tumors, arising from follicular cells, which are observed in two or more first-degree relatives in the absence of predisposing environmental factors."
    explanation: Adds the explicit exclusion of predisposing environmental factors (notably radiation exposure) to the definition.
  - reference: PMID:31247975
    reference_title: Current Knowledge of Germline Genetic Risk Factors for the Development of Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Approximately 5%-15% of NMTC cases are thought to be of familial origin (FNMTC), which is defined as the occurrence of the disease in three or more first-degree relatives of the patient."
    explanation: Documents the competing stricter three-relative definition and the case fraction that accompanies it.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "According to his mathematical simulation, 62–69% of 2-hit families are sporadic occurrences and thus, only families with 3 or more affected first-degree relatives should be considered for clinical and genetic investigations of FNMTC."
    explanation: >-
      The Charkes probability argument quantifying how much of the two-relative
      definition is coincidental clustering; PARTIAL because the same review
      goes on to argue that two-case families should not be excluded outright.
      See the fnmtc-two-relative-definition discussion.
- name: Neck Ultrasound With Ultrasound-Guided Fine-Needle Aspiration
  description: >-
    Evaluation of a detected nodule follows standard differentiated-thyroid-cancer
    practice and is not modified by family history: serum TSH plus high-resolution
    thyroid and cervical-node ultrasound, then ultrasound-guided fine-needle
    aspiration according to sonographic risk pattern and nodule size, reported with
    Bethesda cytology. This is the diagnostic workup of an index nodule, and is
    distinct from the separate question of whether to run surveillance ultrasound
    on unaffected relatives at all (next entry). FNMTC screening cohorts have used
    a lower biopsy threshold than routine practice - nodules greater than 0.5 cm.
  diagnosis_term:
    preferred_term: Ultrasound-Guided Fine-Needle Aspiration
    term:
      id: NCIT:C137833
      label: Ultrasound-Guided Fine-Needle Aspiration
  evidence:
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A prospective cohort study was performed with yearly screening using neck ultrasound and fine-needle aspiration biopsy of thyroid nodule(s) >0.5 cm in at-risk individuals whose relatives were diagnosed with familial non-medullary thyroid cancer (FNMTC)."
    explanation: >-
      Documents the ultrasound-plus-FNA protocol and the 0.5 cm biopsy size
      threshold used in the reference FNMTC cohort.
- name: Germline Genetic Testing
  description: >-
    Testing is phenotype-directed. When syndromic features are present, targeted
    germline testing of APC, PTEN, DICER1, PRKAR1A or WRN (or a multigene
    hereditary-cancer panel) is appropriate and actionable. For apparently isolated
    non-syndromic kindreds there is no validated predictive panel; exome or genome
    sequencing of multiple affected and unaffected relatives with segregation
    analysis is a research-grade approach best reserved for families with three or
    more affected members.
  evidence:
  - reference: PMID:35255942
    reference_title: Genetic susceptibility to hereditary non-medullary thyroid cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although syndromic NMTC has well-known genetic risk factors, the gene(s) responsible for the vast majority of non-syndromic FNMTC cases are yet to be identified."
    explanation: Supports the split between actionable syndromic testing and the absence of a validated non-syndromic panel.
  - reference: PMID:31247975
    reference_title: Current Knowledge of Germline Genetic Risk Factors for the Development of Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Research carried out to date identifies fourteen genes (DICER1, FOXE1, PTCSC2, MYH9, SRGAP1, HABP2, BRCA1, CHEK2, ATM, RASAL1, SRRM2, XRCC1, TITF-1/NKX2.1, PTCSC3) associated with vulnerability to FNMTC that are not related to hereditary syndromes."
    explanation: Enumerates the non-syndromic candidate gene list, none of which constitutes a validated clinical predictive test.
- name: Surveillance Ultrasound of At-Risk First-Degree Relatives
  description: >-
    Because no germline test is available for non-syndromic FNMTC, imaging
    surveillance of unaffected first-degree relatives is the only screening
    option - and whether to offer it is genuinely unresolved, with the yield
    depending sharply on family size. In a prospective NIH cohort, yearly neck
    ultrasound with fine-needle aspiration of nodules greater than 0.5 cm
    detected thyroid cancer in 4.6% of at-risk members of two-affected-member
    families (close to the background nodule-derived detection rate) versus
    22.7% in families with three or more affected members; screen-detected
    cancers were smaller, less often node-positive, and required less extensive
    surgery and less radioiodine. Conversely, a prospective study of 72 children
    and adolescents with a single affected parent found no cancers over five
    years and concluded screening was unwarranted in that setting. The
    defensible synthesis is individualised surveillance after counselling for
    kindreds with three or more affected relatives, and shared decision-making
    rather than routine screening for two-case families, with overdiagnosis as
    the principal harm.
  diagnosis_term:
    preferred_term: Cancer Screening
    term:
      id: NCIT:C15406
      label: Cancer Screening
  evidence:
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thyroid cancer was detected by screening in 4.6% (2/43) of at-risk individuals from families with two members affected, and in 22.7% (15/66) of at-risk members from families with three or more patients affected (p = 0.01)."
    explanation: >-
      Quantifies the screening-yield gradient by number of affected relatives -
      the empirical basis for restricting surveillance to larger kindreds.
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Screening of at-risk family members resulted in earlier detection of low-risk FNMTC and was associated with a less aggressive initial treatment."
    explanation: The benefit claim for surveillance in at-risk relatives.
  - reference: PMID:36124950
    reference_title: Ultrasonography screening in children and adolescents who have one parent with familial non-medullary thyroid carcinoma.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "The present results suggest that US screening is not necessary in children or adolescents when one parent has a diagnosis of FNMTC"
    explanation: >-
      Prospective paediatric evidence against routine ultrasound screening in
      two-relative families - the direct counterweight to the NIH result.
clinical_trials:
- name: NCT01109420
  description: >-
    The NIH prospective natural-history and screening cohort in familial
    non-medullary thyroid cancer, and the trial datum behind the central
    management question in this entry - whether to screen unaffected
    first-degree relatives. It enrols individuals aged 7 and over with two
    affected first-degree relatives, re-screens non-cancer participants yearly
    with non-invasive imaging, and is the source of the 4.6% versus 22.7%
    screening-yield gradient by pedigree size reported in PMID:28657510 and
    curated on the Surveillance Ultrasound diagnosis entry. Its stated
    objectives - natural history, best screening strategy, and susceptibility
    gene identification - map onto the three largest open questions in this
    entry.
  target_phenotypes:
  - preferred_term: Non-medullary thyroid carcinoma
    term:
      id: HP:0040198
      label: Non-medullary thyroid carcinoma
  - preferred_term: Thyroid nodule
    term:
      id: HP:0025388
      label: Thyroid nodule
  evidence:
  - reference: clinicaltrials:NCT01109420
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "To determine the best screening strategy for FNMTC."
    explanation: >-
      The trial's own statement that relative-screening strategy is an
      unresolved question being studied prospectively - the registry-level
      counterpart to the unresolved screening recommendation curated here.
  - reference: clinicaltrials:NCT01109420
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals at least 7 years of age who have two first-degree relatives (e.g., parents, children, siblings) who have or have had non-medullary thyroid cancer or a documented diagnosis of non-medullary thyroid cancer and one living relative with documented non-medullary thyroid cancer."
    explanation: >-
      Documents that the cohort is assembled under the two-first-degree-relative
      definition, which is exactly the criterion questioned in the
      fnmtc-two-relative-definition discussion - so its yield estimates inherit
      that dilution.
differential_diagnoses:
- name: Classic familial adenomatous polyposis
  description: >-
    Germline APC variants cause familial adenomatous polyposis / Gardner syndrome,
    in which thyroid carcinoma - characteristically the cribriform-morular pattern,
    in young women - occurs alongside colorectal adenomatous polyposis. Identifying
    APC moves the family out of non-syndromic FNMTC and into a syndrome with its
    own colorectal surveillance and prophylactic colectomy pathway. See the
    Classic Familial Adenomatous Polyposis entry in this knowledge base.
  disease_term:
    preferred_term: classic familial adenomatous polyposis
    term:
      id: MONDO:0021055
      label: classic familial adenomatous polyposis
  distinguishing_features:
  - Colorectal adenomatous polyposis, often with congenital hypertrophy of the retinal pigment epithelium, desmoid tumors and osteomas.
  - Cribriform-morular thyroid carcinoma histology, strongly female-predominant and young-onset.
  - A pathogenic germline APC variant is identifiable, unlike in non-syndromic FNMTC.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Lists familial adenomatous polyposis among the syndromes that must be recognized and excluded.
- name: Cowden syndrome
  description: >-
    Germline PTEN variants cause Cowden syndrome / PTEN hamartoma tumor syndrome,
    in which follicular and papillary thyroid carcinoma occur together with
    macrocephaly, mucocutaneous hamartomas, breast carcinoma and endometrial
    carcinoma. See the Cowden Syndrome and PTEN Hamartoma Tumor Syndrome entries,
    which already curate non-medullary thyroid carcinoma as a component phenotype.
  disease_term:
    preferred_term: Cowden syndrome
    term:
      id: MONDO:0016063
      label: Cowden disease
  distinguishing_features:
  - Macrocephaly, trichilemmomas and other mucocutaneous hamartomas.
  - Multi-organ tumor spectrum including breast and endometrial carcinoma.
  - A pathogenic germline PTEN variant is identifiable.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Lists Cowden syndrome among the syndromes that must be excluded before diagnosing non-syndromic FNMTC.
- name: Carney complex
  description: >-
    Germline PRKAR1A variants cause Carney complex, in which thyroid follicular
    neoplasia occurs with lentigines, cardiac myxomas, primary pigmented nodular
    adrenocortical disease and other endocrine tumors.
  disease_term:
    preferred_term: Carney complex
    term:
      id: MONDO:0015285
      label: Carney complex
  distinguishing_features:
  - Spotty skin pigmentation (lentigines) and cardiac or cutaneous myxomas.
  - Primary pigmented nodular adrenocortical disease with Cushing syndrome.
  - A pathogenic germline PRKAR1A variant is identifiable.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Lists Carney complex type 1 among the syndromes that must be excluded.
- name: Werner syndrome
  description: >-
    Biallelic germline WRN variants cause Werner syndrome, a segmental progeroid
    RecQ-helicase disorder with a characteristic neoplasm spectrum that includes
    thyroid carcinoma.
  disease_term:
    preferred_term: Werner syndrome
    term:
      id: MONDO:0010196
      label: Werner syndrome
  distinguishing_features:
  - Premature ageing phenotype with scleroderma-like skin, cataracts, short stature and early atherosclerosis.
  - Autosomal recessive rather than dominant transmission.
  - Biallelic pathogenic WRN variants are identifiable.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Lists Werner syndrome among the syndromes that must be excluded.
- name: DICER1-related tumor predisposition
  description: >-
    Germline DICER1 variants cause a tumor predisposition syndrome in which
    multinodular goiter and differentiated thyroid carcinoma occur alongside
    pleuropulmonary blastoma, ovarian Sertoli-Leydig cell tumor and cystic nephroma.
  disease_term:
    preferred_term: DICER1-related tumor predisposition
    term:
      id: MONDO:0100216
      label: DICER1-related tumor predisposition
  distinguishing_features:
  - Pleuropulmonary blastoma, cystic nephroma or ovarian Sertoli-Leydig cell tumor in the pedigree.
  - Early-onset multinodular goiter, often before the carcinoma.
  - A pathogenic germline DICER1 variant is identifiable.
  evidence:
  - reference: PMID:27807061
    reference_title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome."
    explanation: Lists DICER1 syndrome among the syndromes that must be excluded.
- name: Medullary thyroid carcinoma
  description: >-
    Medullary thyroid carcinoma arises from calcitonin-producing parafollicular C
    cells, not from follicular cells, and its familial form (MEN2A, MEN2B, familial
    medullary thyroid carcinoma) is caused by germline RET variants with a
    well-defined genotype-directed prophylactic thyroidectomy pathway. It is
    excluded by definition from FNMTC and is curated separately in the
    Medullary Thyroid Carcinoma entry. Confusing the two is the principal named-entity
    hazard in this disease area.
  disease_term:
    preferred_term: medullary thyroid gland carcinoma
    term:
      id: MONDO:0015277
      label: medullary thyroid gland carcinoma
  distinguishing_features:
  - Parafollicular C cell rather than follicular cell origin.
  - Elevated serum calcitonin and carcinoembryonic antigen.
  - Germline RET variants with established genotype-risk-directed prophylactic thyroidectomy, unlike non-syndromic FNMTC where no such pathway exists.
  evidence:
  - reference: PMID:31247975
    reference_title: Current Knowledge of Germline Genetic Risk Factors for the Development of Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Medullary thyroid carcinoma (MTC) develops from neuroendocrine C cells, and can occur sporadically or as a familial condition."
    explanation: Establishes the C-cell origin that distinguishes medullary from non-medullary familial thyroid cancer.
- name: Radiation-associated thyroid carcinoma
  description: >-
    Shared childhood neck irradiation within a family can produce apparent
    aggregation of thyroid carcinoma without inherited susceptibility. Excluding a
    common environmental exposure is part of the FNMTC definition.
  distinguishing_features:
  - A documented history of therapeutic or accidental neck irradiation, typically in childhood, shared by affected relatives.
  - Aggregation follows the exposure rather than the pedigree structure.
  evidence:
  - reference: PMID:33488516
    reference_title: Clinical and Genetic Features of a Large Monocentric Series of Familial Non-Medullary Thyroid Cancers.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "which are observed in two or more first-degree relatives in the absence of predisposing environmental factors"
    explanation: The definitional requirement to exclude a shared predisposing environmental exposure such as radiation.
- name: Coincidental familial clustering of sporadic differentiated thyroid carcinoma
  description: >-
    Chance co-occurrence of sporadic papillary or follicular thyroid carcinoma
    within a family is the single most common alternative explanation for a
    two-affected-relative pedigree, and is the reason the two-relative
    definition is contested. Thyroid cancer is common and its detected incidence
    has risen sharply with ultrasound use, so a substantial fraction of two-case
    families do not represent inherited disease at all. Unlike the syndromic
    differentials this one cannot be excluded by a test - it is excluded
    probabilistically, by pedigree size.
  disease_term:
    preferred_term: differentiated thyroid carcinoma
    term:
      id: MONDO:0015447
      label: differentiated thyroid carcinoma
  distinguishing_features:
  - Exactly two affected first-degree relatives, with no third case and no unusually young onset.
  - Both cases detected incidentally during the ultrasound era rather than presenting clinically.
  - No excess of benign nodular thyroid disease among unaffected relatives.
  evidence:
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the presence of only two affected members in kindreds may represent a fortuitous association of the disease"
    explanation: States the coincidental-clustering differential explicitly.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "According to his mathematical simulation, 62–69% of 2-hit families are sporadic occurrences and thus, only families with 3 or more affected first-degree relatives should be considered for clinical and genetic investigations of FNMTC."
    explanation: >-
      Quantifies how large this differential is - on the Charkes simulation the
      majority of two-case families fall into it.
- name: Familial multinodular goiter
  description: >-
    Autosomal dominant familial multinodular goitre is common, especially in
    iodine-deficient regions, and can be mistaken for or coexist with FNMTC.
    Because benign nodular thyroid disease is itself enriched in FNMTC kindreds,
    a family with many nodular relatives and one or two carcinomas is genuinely
    ambiguous. Susceptibility to multinodular goitre and to non-medullary
    thyroid carcinoma may in fact be partly shared, so this is a boundary case
    rather than a clean exclusion.
  disease_term:
    preferred_term: multinodular goiter
    term:
      id: MONDO:0000334
      label: multinodular goiter
  distinguishing_features:
  - Nodular disease without histologically confirmed carcinoma in the affected relatives.
  - High background goitre prevalence in the population of origin (iodine deficiency).
  - Aggregation of goitre rather than of carcinoma across the pedigree.
  evidence:
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In areas with iodine deficiency MNG is common and, although the population incidence of MNG far exceeds that of thyroid cancer, there is also evidence that genetic susceptibility to MNG and to NMTC may be related"
    explanation: >-
      Documents both the confounding and the possibility of genuinely shared
      susceptibility, which is why this is curated as a boundary case.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In fact, families segregating an autosomal dominant trait for MNG often include cases of NMTC."
    explanation: >-
      States the co-segregation of multinodular goitre and non-medullary thyroid
      cancer within kindreds directly.
discussions:
- discussion_id: fnmtc-habp2-controversy
  kind: CONTROVERSY
  status: OPEN
  attaches_to:
  - genetic#HABP2
  prompt: >-
    Does germline HABP2 p.G534E confer susceptibility to familial nonmedullary
    thyroid carcinoma in any subset of kindreds, or should the association be
    considered refuted outright?
  rationale: >-
    The 2015 New England Journal of Medicine report of germline HABP2 p.G534E
    cosegregating in a large FNMTC kindred, supported by loss-of-function assays,
    was the highest-profile candidate-gene claim in this field. It was contradicted
    within a year on two independent grounds: failure of cosegregation in other
    kindreds carrying the allele, and an allele frequency of 7-9% in unselected
    populations, which is incompatible with a highly penetrant dominant cancer
    allele. Independent European series are likewise negative. The dismech entry
    therefore types HABP2 as DISPUTED and carries both the original SUPPORT
    evidence and the REFUTE evidence, so downstream consumers see the controversy
    rather than a one-sided assertion. The residual open question is whether the
    variant could act as a very-low-penetrance modifier in some ancestries - a
    hypothesis that current data neither establish nor formally exclude - not
    whether it is a clinically actionable predisposition allele, which it is not.
  proposed_experiments:
  - name: Ancestry-matched case-control association testing of HABP2 p.G534E
    experiment_id: fnmtc-exp-habp2-casecontrol
    description: Ancestry-matched case-control association testing of HABP2 p.G534E at sufficient power to detect an odds ratio below 1.3.
  - name: Formal cosegregation meta-analysis across all published FNMTC
    experiment_id: fnmtc-exp-habp2-cosegregation
    description: Formal cosegregation meta-analysis across all published FNMTC kindreds carrying the allele.
- discussion_id: fnmtc-genetic-architecture
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Inherited Non-Syndromic Susceptibility in Thyroid Follicular Cells
  prompt: >-
    What is the genetic architecture of non-syndromic FNMTC - polygenic
    accumulation of common low-effect alleles, family-specific oligogenic
    combinations of rare alleles, or a set of as-yet-unidentified moderate-penetrance
    monogenic causes?
  rationale: >-
    The susceptibility genes for roughly 95% of FNMTC cases remain uncharacterized
    despite three decades of linkage, GWAS and exome/genome sequencing. Reviews
    describe the trait as polygenic with multiple low- to moderate-penetrance
    genes, yet individual kindreds segregate apparent autosomal dominance and each
    family tends to carry its own candidate lesion. These three models are not
    mutually exclusive and cannot currently be distinguished, which is why no
    predictive gene panel exists for isolated kindreds. This entry asserts the
    polygenic and autosomal-dominant-with-reduced-penetrance models, for which
    quotable evidence exists, and deliberately does NOT bind an oligogenic
    inheritance term (HP:0010983), because no cited source demonstrates
    joint transmission of two or more specified loci in an FNMTC pedigree.
  proposed_experiments:
  - name: Polygenic risk score construction from thyroid cancer
    experiment_id: fnmtc-exp-prs-multiplex
    description: Polygenic risk score construction from thyroid cancer GWAS loci, tested for enrichment in multiplex FNMTC kindreds versus matched sporadic cases.
  - name: Large-scale trio and multiplex-family whole-genome sequencing with
    experiment_id: fnmtc-exp-wgs-multiplex
    description: Large-scale trio and multiplex-family whole-genome sequencing with joint linkage and rare-variant burden analysis across ancestries.
  - name: Systematic testing for two-locus joint transmission in
    experiment_id: fnmtc-exp-two-locus-transmission
    description: Systematic testing for two-locus joint transmission in kindreds carrying more than one candidate rare allele, which would be required before an oligogenic inheritance term could be asserted.
- discussion_id: fnmtc-aggressiveness-ascertainment
  kind: CONTROVERSY
  status: OPEN
  attaches_to:
  - phenotype#Earlier Age at Onset in Successive Generations
  prompt: >-
    Is the reported clinical anticipation and increased aggressiveness of familial
    tumors a biological property of FNMTC, or an artefact of ascertainment and
    intensified surveillance of known families?
  rationale: >-
    Multiple independent series report earlier onset, more multifocality and
    bilaterality, and higher nodal metastasis rates in second-generation affected
    relatives, and matched case-control studies find increased biological
    aggressiveness. But once a family is identified, its younger members are
    imaged more intensively and earlier, which by itself produces earlier apparent
    age at diagnosis and smaller detected tumors. No repeat-expansion or other
    molecular anticipation mechanism has been demonstrated. Critically, the largest
    contemporary series finds a more aggressive presentation that does not
    translate into a worse outcome - the pattern one expects from detection bias
    plus effective treatment, and the reason major guidelines have not endorsed
    escalating surgery or universal relative screening on the basis of family
    history alone.
  proposed_experiments:
  - name: Prospective screening-protocol-matched comparison of familial and sporadic
    experiment_id: fnmtc-exp-screening-matched-cohort
    description: Prospective screening-protocol-matched comparison of familial and sporadic cohorts, with lead-time and length-time bias correction.
  - name: Registry-based analysis of familial versus sporadic outcomes
    experiment_id: fnmtc-exp-registry-detection-mode
    description: Registry-based analysis of familial versus sporadic outcomes stratified by whether the index case was detected by family screening or by symptoms.
    decision_criterion: >-
      Attenuation of the familial-versus-sporadic difference within the
      symptom-detected stratum would indicate the effect is substantially a
      product of detection mode rather than of tumour biology.
  - name: Prospective parent-offspring germline telomere-length measurement
    experiment_id: fnmtc-exp-parent-offspring-telomere-length
    description: >-
      Measure germline leukocyte telomere length prospectively in
      parent-offspring pairs within the same FNMTC kindreds, to test the one
      proposed molecular substrate for anticipation directly and to reconcile
      the telomere-shortening and telomere-lengthening literatures collected
      under the telomere_length_predisposition hypothesis group.
    decision_criterion: >-
      A systematic intergenerational change in telomere length that tracks age
      at diagnosis would supply the missing molecular substrate and move the
      clinical_anticipation hypothesis off ALTERNATIVE; no such gradient would
      leave ascertainment as the parsimonious explanation.
  evidence:
  - reference: PMID:25637073
    reference_title: "Endocrine tumours: familial nonmedullary thyroid carcinoma is a more aggressive disease: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "FNMTC possessed more aggressive biological behaviors, characterized by younger age at diagnosis (SMD=-0.91, 95% CI: -1.59 to -0.22), higher risk of multifocal (OR=1.50, 95% CI: 1.32 to 1.71), bilateral (OR=1.29, 95% CI: 1.00 to 1.66), extrathyroidal invasion (OR=1.20, 95% CI: 1.02 to 1.41), and lymph node metastasis (OR=1.18, 95% CI: 1.01 to 1.38)."
    explanation: >-
      Pooled effect sizes for the "more aggressive presentation" side of the
      controversy, across 12 studies and 12,741 participants.
  - reference: PMID:25637073
    reference_title: "Endocrine tumours: familial nonmedullary thyroid carcinoma is a more aggressive disease: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "FNMTC patients had an increased rate of recurrence (OR=1.72, 95% CI: 1.34 to 2.20) and decreased disease-free survival (DFS) (HR=1.83, 95% CI: 1.34 to 2.52) in comparison with SNMTC patients."
    explanation: >-
      The strongest quantitative claim that the presentation difference does
      translate into a worse outcome - the counter to the detection-bias reading.
  - reference: PMID:40908394
    reference_title: "Relationship between affected family members and clinical aggressiveness in Familial non-medullary thyroid carcinoma: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clinical aggressiveness of FNMTC escalates with increasing numbers of affected family members."
    explanation: >-
      2025 meta-analysis of 3,036 FNMTC and 10,497 sporadic patients showing a
      dose-response with pedigree size. A dose-response is harder to explain by
      detection bias alone and is the strongest argument for a real biological
      component.
  - reference: PMID:40908394
    reference_title: "Relationship between affected family members and clinical aggressiveness in Familial non-medullary thyroid carcinoma: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "distant metastasis (OR: 2.43 and 3.93)"
    explanation: >-
      Distant metastasis carries the largest familial-versus-sporadic effect of
      any feature - and, unlike tumour size or nodal status, is the least
      plausible product of earlier detection.
  - reference: PMID:40392709
    reference_title: Comparison of Progression-Free Survival in Familial Non-Medullary Thyroid Cancer and Sporadic Differentiated Thyroid Cancer Patients.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "No difference in PFS between FNMTC and sDTC patients suggests comparable responsiveness to standard therapy."
    explanation: >-
      Matched cohort finding no progression-free-survival penalty. Note the
      important caveat that it matched 100% on ATA recurrence risk, i.e. it
      conditions on the aggressiveness variable in dispute, so it argues more
      directly that familial tumours respond normally to therapy than that they
      are biologically equivalent.
  - reference: PMID:28942234
    reference_title: "Second generation of familial nonmedullary thyroid carcinoma: A meta-analysis on the clinicopathologic features and prognosis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "There was significant difference between the first and second generation of parent/offspring type FNMTC in the age of onset (SMD = -1.20, 95% CI: -2.38, -0.03, p = 0.045), gender distribution (OR = 0.48, 95% CI: 0.25, 0.90, p = 0.022) and lymph node metastasis (OR = 1.84, 95%CI: 1.16, 2.92, p = 0.01), while no significant difference in other variables."
    explanation: >-
      Delimits, rather than refutes, the generational claim. In this six-study
      424-subject meta-analysis three variables reached significance - age of
      onset, gender distribution, and lymph node metastasis (OR 1.84) - and the
      authors conclude the second generation is at higher risk. Tagged PARTIAL
      because that is a narrow and partly non-aggressiveness set of variables on
      a small pooled sample, and because a generational difference in nodal
      metastasis is exactly what intensified surveillance of known families
      would NOT predict, so it cuts against the pure-ascertainment reading
      rather than supporting it. An earlier version of this item quoted only the
      bare trailing clause and described significance as limited to age and sex,
      omitting the lymph node result; that misread the source and is corrected
      here.
- discussion_id: fnmtc-mondo-granularity
  kind: INTERPRETATION
  status: OPEN
  prompt: >-
    Which MONDO term should host FNMTC, and should the entity that hosts it
    include the syndromic forms or only the non-syndromic (pure) form?
  rationale: >-
    Neither available MONDO term is a clean fit, and the mismatch is worth
    recording rather than papering over. MONDO:0017895 ("familial papillary or
    follicular thyroid carcinoma") carries `subset: obsoletion_candidate`, is a
    direct child of MONDO:0017896 that it effectively duplicates, and takes the
    Orphanet synonym "familial pure nonmedullary thyroid carcinoma", which reads
    as the non-syndromic form specifically. The obvious fallback does NOT
    resolve the mismatch either: MONDO:0017896 is itself defined as "a rare
    non-syndromic form of thyroid cancer" and carries `subset: disease_grouping`
    / `subset: ordo_group_of_disorders`, so anchoring there still excludes the
    syndromic forms and additionally anchors a Disease entry on a grouping term.
    This entry takes option (b) below: it anchors `disease_term` on
    MONDO:0017896, scopes itself to the non-syndromic form, keeps MONDO:0017895
    as a skos:closeMatch, and models the recognised syndromic causes (APC, PTEN,
    PRKAR1A, WRN, DICER1) as differential_diagnoses plus typed `genetic`
    entries that point at their own full dismech entries, rather than as
    has_subtypes of this one. The genuine options are (a) treat this entry as a
    clinical umbrella carrying both non-syndromic loci and syndromic forms as
    has_subtypes, matching how the clinical literature partitions FNMTC but
    contradicting both MONDO definitions; (b) the scoping used here; or (c)
    model the clinical umbrella as a dismech Grouping over the existing
    syndromic disease entries plus this non-syndromic Disease entry, which is
    exactly what the Grouping class exists for. Option (c) is probably the right
    long-term answer but is a lump-versus-split judgement that should be made
    once, deliberately, for the whole hereditary-cancer area rather than
    unilaterally here - flagging for human adjudication by @cmungall.
- discussion_id: fnmtc-two-relative-definition
  kind: OPEN_QUESTION
  status: OPEN
  attaches_to:
  - diagnosis#Pedigree-Based Clinical Definition
  prompt: >-
    Is the conventional two-affected-first-degree-relative definition of FNMTC
    fit for purpose, or should the threshold be three?
  rationale: >-
    This is not a terminological quibble - it silently determines every
    statistic in this entry, because a cohort assembled under the two-relative
    rule is diluted with coincidental clusters and will understate any true
    familial effect. For raising the threshold: a probability argument (Charkes)
    concludes that 62-69% of two-case families are coincidental sporadic
    clustering; prospective screening yield tracks the same gradient, at 4.6%
    cancer detection in two-case families versus 22.7% in families with three or
    more affected members; and a 2025 meta-analysis finds that clinical
    aggressiveness escalates with the number of affected relatives, proposing
    that three-or-more-case families be treated as a distinct high-risk
    subgroup. Against raising it: population-registry data show that more than
    90% of familial cancer clusters contain only two affected members, so a
    three-relative rule would exclude most genuinely low-penetrance familial
    disease - precisely the disease that the polygenic model predicts should
    dominate. The definition used in this entry remains two or more first-degree
    relatives, matching the clinical literature, with the dilution caveat
    carried explicitly here and in the Pedigree-Based Clinical Definition
    diagnosis entry.
  proposed_experiments:
  - name: Pedigree-size-stratified reanalysis of pooled FNMTC cohorts
    experiment_id: fnmtc-exp-pedigree-size-stratified-reanalysis
    description: >-
      Reanalyse pooled familial cohorts with every outcome reported separately
      for two-case and three-or-more-case kindreds, rather than pooling them
      under a single FNMTC label.
    decision_criterion: >-
      If effect estimates in two-case families collapse toward the sporadic
      null while three-or-more-case families retain them, the two-relative
      definition is diluting the entity and the threshold should be raised for
      research use even if retained clinically.
  evidence:
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "According to his mathematical simulation, 62–69% of 2-hit families are sporadic occurrences and thus, only families with 3 or more affected first-degree relatives should be considered for clinical and genetic investigations of FNMTC."
    explanation: The probability argument for raising the threshold to three relatives.
  - reference: PMID:33025555
    reference_title: "Familial non-medullary thyroid cancer: a critical review."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "more than 90% of familial cancers were in families with two affected members"
    explanation: >-
      The counterargument - a three-relative rule would exclude the great
      majority of familial clusters, i.e. most of the low-penetrance disease the
      polygenic model predicts.
  - reference: PMID:28657510
    reference_title: Results of Screening in Familial Non-Medullary Thyroid Cancer.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thyroid cancer was detected by screening in 4.6% (2/43) of at-risk individuals from families with two members affected, and in 22.7% (15/66) of at-risk members from families with three or more patients affected (p = 0.01)."
    explanation: Empirical screening-yield gradient supporting stratification by pedigree size.
  - reference: PMID:40908394
    reference_title: "Relationship between affected family members and clinical aggressiveness in Familial non-medullary thyroid carcinoma: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clinical aggressiveness of FNMTC escalates with increasing numbers of affected family members."
    explanation: >-
      2025 meta-analytic support for treating pedigree size as a graded risk
      variable rather than a binary inclusion criterion.
notes: >-
  Scope and relationship to sibling entries. FNMTC is the familial *predisposition*
  entity; the tumors it predisposes to are histologically and molecularly the
  sporadic entities already curated in this knowledge base -
  Papillary_Thyroid_Carcinoma, Thyroid_Follicular_Carcinoma,
  BRAF_Mutant_Thyroid_Cancer and RET_Fusion_Thyroid_Cancer. Their somatic-driver
  content (BRAF V600E, RAS, RET/PTC and NTRK fusions, TERT promoter mutation) is
  deliberately NOT duplicated here; this entry models only the germline
  susceptibility layer and the way it changes tumor multiplicity, age at
  presentation, and family management. Likewise the syndromic differentials are
  cross-referenced under differential_diagnoses rather than re-curated:
  Classic_Familial_Adenomatous_Polyposis, Cowden_Syndrome,
  PTEN_Hamartoma_Tumor_Syndrome and Medullary_Thyroid_Carcinoma already exist.

  Ontology anchoring. `disease_term` is bound to MONDO:0017896 rather than to
  MONDO:0017895, the term named in the originating issue, because MONDO tags
  MONDO:0017895 with `subset: obsoletion_candidate` and places it as a direct
  child of MONDO:0017896 that it effectively duplicates. MONDO:0017895 is retained
  under `mappings.mondo_mappings` as a skos:closeMatch. Neither term is a clean
  fit for a syndromic-inclusive umbrella - MONDO:0017896 is itself defined as
  "a rare non-syndromic form of thyroid cancer" and carries
  `subset: disease_grouping` - which is why this entry scopes to the
  non-syndromic form and treats the syndromic causes as differentials. The open
  lump-versus-split question, including whether a dismech Grouping would model
  the clinical umbrella better, is tracked in the `fnmtc-mondo-granularity`
  discussion and flagged for human adjudication.

  Mechanistic hypothesis groups. Three explanatory models are declared under
  `mechanistic_hypotheses` and wired to the causal edges that belong to them, so
  that consumers can filter the pathograph by which model they accept:
  `habp2_g534e_susceptibility` (DEPRECATED - the refuted HABP2 branch, retained
  deliberately rather than deleted), `telomere_length_predisposition` (EMERGING -
  carries the directionally opposite telomere-shortening and telomere-lengthening
  arms together, because they may describe different subgroups), and
  `clinical_anticipation` (ALTERNATIVE, never CANONICAL - the observation is
  real but its interpretation as true anticipation is not established).

  Evidence limitations. Three limitations should be carried forward by any
  consumer of this entry. First, two-case families are substantially contaminated
  by coincidental clustering of a common sporadic cancer, so any statistic
  computed over two-case kindreds overstates the inherited component. Second, most
  candidate-gene reports are single-family or underpowered and lack independent
  replication - the HABP2 episode is the cautionary case, and SRRM2, MAP2K5 and
  DUOX2 are in the same category. Third, screening intensity within known families
  systematically distorts apparent age at onset, tumor size, and aggressiveness.
  A dedicated Orphanet-sourced epidemiology record could not be added because the
  local Orphadata snapshot is unavailable in this working tree.
references:
- reference: PMID:33025555
  title: "Familial non-medullary thyroid cancer: a critical review."
- reference: PMID:35255942
  title: Genetic susceptibility to hereditary non-medullary thyroid cancer.
- reference: PMID:35295987
  title: "Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys."
- reference: PMID:27807061
  title: "Familial non-medullary thyroid cancer: unraveling the genetic maze."
- reference: PMID:38571492
  title: Chromosomal localization of mutated genes in non-syndromic familial thyroid cancer.
- reference: PMID:37438605
  title: Pathogenesis of cancers derived from thyroid follicular cells.
- reference: PMID:24761742
  title: DICER1-Related Tumor Predisposition.
  tags:
  - GeneReviews

📚

References & Deep Research

References

7

PMID:33025555

Familial non-medullary thyroid cancer: a critical review.

No top-level findings curated for this source.

PMID:35255942

Genetic susceptibility to hereditary non-medullary thyroid cancer.

No top-level findings curated for this source.

PMID:35295987

Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys.

No top-level findings curated for this source.

PMID:27807061

Familial non-medullary thyroid cancer: unraveling the genetic maze.

No top-level findings curated for this source.

PMID:38571492

Chromosomal localization of mutated genes in non-syndromic familial thyroid cancer.

No top-level findings curated for this source.

PMID:37438605

Pathogenesis of cancers derived from thyroid follicular cells.

No top-level findings curated for this source.

PMID:24761742

DICER1-Related Tumor Predisposition.

No top-level findings curated for this source.

Deep Research

1

Falcon ▸

Familial Nonmedullary Thyroid Carcinoma: Disease-Characteristics Report

Edison Scientific Literature 38 citations 2026-07-31T18:02:16.130419

Familial Nonmedullary Thyroid Carcinoma: Disease-Characteristics Report

Executive summary

Familial nonmedullary thyroid carcinoma (FNMTC) is familial aggregation of follicular-cell-derived thyroid carcinoma—predominantly papillary thyroid carcinoma (PTC)—rather than medullary thyroid carcinoma. The conventional clinical definition is NMTC in at least two first-degree relatives, after excluding a recognized tumor-predisposition syndrome. However, only an estimated 31–38% of two-case families may represent true inherited disease, versus approximately 96% of families with at least three affected members. Thus, ≥3 affected relatives is a more specific research definition. FNMTC comprises roughly 5–15% of NMTC in recent reviews; approximately 5% of familial cases are explained by recognized syndromes, while most nonsyndromic cases remain genetically unresolved. (yang2016familialnonmedullarythyroid pages 13-14, sanchezares2022susceptibilitygenesand pages 1-2, kamani2022geneticsusceptibilityto pages 1-2)

The principal current conclusion is that nonsyndromic FNMTC is not one Mendelian disorder. It is genetically heterogeneous, usually modeled as autosomal-dominant susceptibility with incomplete, age-dependent penetrance and variable expressivity, or as a polygenic trait. No single germline gene explains most isolated families. Confirmed, clinically actionable genes mainly belong to syndromic disease—APC, PTEN, DICER1, PRKAR1A, and WRN—whereas FOXE1, SRGAP1, NKX2-1, HABP2, MAP2K5, DUOX2, CHEK2, POT1 and numerous other candidates require family-specific interpretation and, for many, independent replication. (capezzone2021familialnonmedullarythyroid pages 2-4, capezzone2021familialnonmedullarythyroid pages 4-5, sanchezares2022susceptibilitygenesand pages 1-2, kamani2022geneticsusceptibilityto pages 11-12)

1. Disease information

Definition, category, and synonyms

Category: rare/familial endocrine malignancy; hereditary cancer predisposition; follicular-cell-derived thyroid carcinoma.

Common labels are familial nonmedullary thyroid carcinoma, familial non-medullary thyroid cancer, familial nonmedullary thyroid cancer, and—when all tumors are papillary—familial papillary thyroid carcinoma (FPTC). FPTC is a subset rather than a complete synonym because follicular, oncocytic/Hürthle-cell, and very rarely anaplastic histologies also occur. Reviews estimate histologic distributions of approximately 85–91% PTC, 6–9.7% follicular carcinoma, and much smaller proportions of Hürthle-cell or anaplastic carcinoma. (yang2016familialnonmedullarythyroid pages 1-2)

A useful exact abstract statement from Capezzone et al. (published online October 2020; journal issue 2021) is: “Familial non-medullary thyroid carcinoma (FNMTC), mainly of papillary histotype (FPTC), is defined by the presence of the disease in two or more first-degree relatives in the absence of other known familial syndromes.” DOI: 10.1007/s40618-020-01435-x. (capezzone2021familialnonmedullarythyroid pages 1-2)

Identifiers and coding

A definitive dedicated MONDO, OMIM, Orphanet, MeSH, ICD-10, or ICD-11 identifier was not established in the retrieved evidence. FNMTC is primarily a clinical familial-aggregation construct, and nonsyndromic disease is genetically heterogeneous rather than a single molecular entity. For production curation, the current releases of these terminologies should therefore be queried directly rather than assigning an unverified identifier. ICD coding ordinarily uses the thyroid malignancy code plus family-history/genetic-susceptibility modifiers; it does not encode the full FNMTC construct. Syndromic cases should additionally receive the identifier for the causal syndrome. (capezzone2021familialnonmedullarythyroid pages 4-5, sanchezares2022susceptibilitygenesand pages 1-2)

The following table provides conservative ontology recommendations; unverified IDs are deliberately not invented.

Domain	Recommended identifier/ontology term	Annotation/use	Evidence caveat
Disease	Familial non-medullary thyroid carcinoma (FNMTC)	Core disease label for hereditary thyroid carcinoma arising from follicular-cell–derived, non-medullary histologies; typically used for disease-level KB entry	Commonly defined clinically as NMTC in ≥2 first-degree relatives, but many experts note families with only 2 cases may include sporadic clustering; stricter research enrichment often uses ≥3 affected relatives (capezzone2021familialnonmedullarythyroid pages 2-4, yang2016familialnonmedullarythyroid pages 13-14, sanchezares2022susceptibilitygenesand pages 1-2)
Disease identifier	MONDO: unverified	MONDO ID should be added only after curation against current MONDO release	A stable MONDO term was not established from available evidence; do not invent ID (sanchezares2022susceptibilitygenesand pages 1-2)
Disease identifier	OMIM: heterogeneous trait / unverified disease-level OMIM	OMIM may be better represented through susceptibility loci/genes and syndromic conditions rather than a single definitive nonsyndromic disease entry	Available evidence emphasizes marked genetic heterogeneity and lack of one confirmed driver gene (capezzone2021familialnonmedullarythyroid pages 4-5, kamani2022geneticsusceptibilityto pages 11-12)
Disease identifier	MeSH / ICD-10 / ICD-11: use broader thyroid carcinoma terms if needed; FNMTC-specific code unverified	For coding, map to broader non-medullary/differentiated thyroid carcinoma terms with a familial modifier in local schema	FNMTC is mainly a clinical/familial aggregation construct rather than a uniquely coded nosologic entity in available sources (capezzone2021familialnonmedullarythyroid pages 2-4, capezzone2021familialnonmedullarythyroid pages 1-2)
Synonym	Familial nonmedullary thyroid carcinoma	Exact synonym/label normalization	Hyphenation varies by source (capezzone2021familialnonmedullarythyroid pages 1-2)
Synonym	Familial non-medullary thyroid cancer	Common literature synonym	Often used interchangeably with carcinoma in reviews (capezzone2021familialnonmedullarythyroid pages 2-4, yang2016familialnonmedullarythyroid pages 1-2)
Synonym	Familial nonmedullary thyroid cancer	Common synonym for search expansion	Includes papillary-predominant familial disease (yang2016familialnonmedullarythyroid pages 1-2, sanchezares2022susceptibilitygenesand pages 1-2)
Synonym	Familial papillary thyroid carcinoma (subset term)	Use when kindred/pathology is specifically papillary thyroid carcinoma	Not synonymous with all FNMTC because follicular and rarer histologies also occur (yang2016familialnonmedullarythyroid pages 1-2, sanchezares2022susceptibilitygenesand pages 1-2)
HPO phenotype	Thyroid carcinoma (HPO term recommended; stable ID not asserted here)	Parent malignant phenotype for affected individuals	Most familial tumors are papillary histology; exact HPO ID not asserted to avoid miscoding (yang2016familialnonmedullarythyroid pages 1-2, sanchezares2022susceptibilitygenesand pages 1-2)
HPO phenotype	Thyroid nodule (HPO term recommended; stable ID not asserted here)	Captures benign or suspicious nodules found in affected relatives and screening	Benign nodules frequently accompany NS-FNMTC; exact HPO ID not asserted here (NCT01109420 chunk 1, sanchezares2022susceptibilitygenesand pages 1-2)
HPO phenotype	Multifocal thyroid carcinoma / multifocal neoplasm (HPO term recommended; stable ID not asserted here)	Important clinicopathologic feature often reported in familial cases	Familial series reported multifocality around 56%; exact HPO wording may require curator choice (cirello2021clinicalandgenetic pages 3-4)
HPO phenotype	Lymph node metastasis (HPO term recommended; stable ID not asserted here)	Use for nodal spread, especially cervical lymph nodes	Familial cases often present with more nodal disease/aggressive features, but outcome may remain similar with treatment (yang2016familialnonmedullarythyroid pages 1-2, cirello2021clinicalandgenetic pages 1-2, kamani2022geneticsusceptibilityto pages 1-2)
HPO phenotype	Lung metastasis (HPO term recommended; stable ID not asserted here)	Use for distant metastatic spread to lung	Present in a minority of reported familial cases (~7% in one monocentric series) (cirello2021clinicalandgenetic pages 3-4)
HPO phenotype	Goiter / multinodular goiter (HPO term recommended; stable ID not asserted here)	Useful for syndromic or non-syndromic familial thyroid disease annotation	Multinodular goiter can co-occur and may be part of some familial definitions in older/pathology literature (sanchezares2022susceptibilitygenesand pages 1-2)
Anatomy	UBERON:0002046 thyroid gland	Primary affected organ for FNMTC	Robust stable anatomy term; disease arises from follicular epithelium (sanchezares2022susceptibilitygenesand pages 1-2, kamani2022geneticsusceptibilityto pages 1-2)
Anatomy	UBERON cervical lymph node term recommended; stable ID unverified here	Secondary site for regional metastasis annotation	Cervical nodal spread is clinically important, but exact UBERON descendant term not asserted without ontology lookup (cirello2021clinicalandgenetic pages 3-4, kamani2022geneticsusceptibilityto pages 1-2)
Cell type	CL:0000501 thyroid follicular cell	Principal cell of origin for non-medullary thyroid carcinoma	Appropriate for papillary/follicular lineage annotation (sanchezares2022susceptibilitygenesand pages 1-2, kamani2022geneticsusceptibilityto pages 1-2)
Biological process	GO:0000165 MAPK cascade	Mechanistic pathway annotation for signaling dysregulation	Supported by WGS/pathway analyses implicating MAPK/ERK signaling, though specific causal germline alterations vary by family (srivastava2019wholegenomesequencing pages 5-7, srivastava2019wholegenomesequencing pages 19-21)
Biological process	PI3K-AKT signaling pathway (GO/Reactome term recommended; stable GO ID not asserted here)	Complementary pathway annotation for predisposition/mechanism	Central pathway implicated in WGS/network analyses; exact ontology ID not asserted here (srivastava2019wholegenomesequencing pages 5-7, srivastava2019wholegenomesequencing pages 19-21)
Biological process	GO:0008283 cell population proliferation	Generic downstream cancer process annotation	Broad downstream consequence rather than FNMTC-specific mechanism (srivastava2019wholegenomesequencing pages 5-7, srivastava2019wholegenomesequencing pages 19-21)
Gene	APC	Syndromic FNMTC gene; annotate when thyroid carcinoma occurs with familial adenomatous polyposis/Gardner syndrome	High-confidence syndromic association, not a confirmed common cause of isolated non-syndromic FNMTC (capezzone2021familialnonmedullarythyroid pages 4-5, yang2016familialnonmedullarythyroid pages 2-4, sanchezares2022susceptibilitygenesand pages 1-2)
Gene	PTEN	Syndromic FNMTC gene; annotate for Cowden/PTEN hamartoma tumor syndrome	Strong syndromic evidence; actionable in appropriate phenotype context (yang2016familialnonmedullarythyroid pages 2-4, sanchezares2022susceptibilitygenesand pages 1-2)
Gene	DICER1	Syndromic predisposition gene for familial thyroid neoplasia	Relevant especially when other DICER1-spectrum manifestations are present (capezzone2021familialnonmedullarythyroid pages 4-5, sanchezares2022susceptibilitygenesand pages 1-2)
Gene	PRKAR1A	Syndromic gene for Carney complex-associated thyroid carcinoma	Use when phenotype supports Carney complex rather than isolated FNMTC (capezzone2021familialnonmedullarythyroid pages 4-5, sanchezares2022susceptibilitygenesand pages 1-2)
Gene	WRN	Syndromic gene for Werner syndrome-associated thyroid carcinoma	Rare syndromic association; not typical isolated FNMTC driver (capezzone2021familialnonmedullarythyroid pages 4-5, sanchezares2022susceptibilitygenesand pages 1-2)
Gene/locus evidence caveat	FOXE1, HABP2, SRGAP1, TITF1/NKX2.1, MAP2K5, DUOX2, POT1, CHEK2 and others as candidate susceptibility genes/loci	Consider as research/candidate annotations, not definitive disease-gene assertions for routine KB causal field unless separately curated	Reviews emphasize heterogeneity, low-to-moderate penetrance, inconsistent replication, and no single confirmed nonsyndromic driver gene (capezzone2021familialnonmedullarythyroid pages 4-5, yang2016familialnonmedullarythyroid pages 13-14, cirello2021clinicalandgenetic pages 1-2, kamani2022geneticsusceptibilityto pages 11-12)
Intervention	NCIT term recommended: Thyroidectomy	Primary definitive local treatment annotation	Total thyroidectomy frequently used in reported familial series; current guidelines generally do not mandate different surgery solely for family history (capezzone2021familialnonmedullarythyroid pages 6-7, cirello2021clinicalandgenetic pages 3-4)
Intervention	NCIT term recommended: Radioactive Iodine Therapy	Adjuvant treatment annotation for selected differentiated thyroid cancers	Applied according to standard differentiated thyroid cancer risk stratification rather than FNMTC-specific evidence (sanchezares2022susceptibilitygenesand pages 1-2)
Intervention	NCIT term recommended: Thyroid-Stimulating Hormone Suppression Therapy	Postoperative endocrine management annotation	Use as standard differentiated thyroid cancer management; FNMTC-specific modification not established (capezzone2021familialnonmedullarythyroid pages 6-7, sanchezares2022susceptibilitygenesand pages 1-2)
Intervention	NCIT term recommended: Kinase Inhibitor Therapy	Targeted systemic treatment annotation for advanced/refractory disease	Because familial and sporadic NMTC share morphology and somatic drivers, similar targeted therapies are currently used when indicated (sanchezares2022susceptibilitygenesand pages 1-2)
Screening/implementation	Neck ultrasound surveillance in at-risk relatives	Real-world screening annotation for high-risk families/research cohorts	Evidence is mixed: one prospective cohort found thyroid cancer in 4.6% of screened relatives from families with 2 affected members, and major guidelines do not currently recommend universal genetic screening of at-risk relatives (capezzone2021familialnonmedullarythyroid pages 4-5, NCT01109420 chunk 1, kamani2022geneticsusceptibilityto pages 14-15)

Table: This compact table lists practical knowledge-base annotations for familial nonmedullary thyroid carcinoma, including disease labels, suggested ontology terms, syndromic genes, mechanisms, and interventions. It also flags where the evidence is strong versus where identifiers or causal claims remain unverified or heterogeneous.

Source granularity

The report synthesizes aggregated disease-level resources, peer-reviewed reviews, family cohorts, tumor-series data, WGS analyses, and an observational registry. It is not derived from an individual EHR. One detailed Italian study included 33 unrelated families, 74 affected and 12 unaffected relatives; a separate WGS study examined 23 affected and three unaffected members of five families. (cirello2021clinicalandgenetic pages 1-2, srivastava2019wholegenomesequencing pages 2-5)

2. Etiology and risk factors

Genetic causation

Two etiologic classes should be separated:

Syndromic FNMTC: thyroid carcinoma is one manifestation of a defined inherited syndrome. Strong gene–syndrome associations include APC–familial adenomatous polyposis/Gardner syndrome, PTEN–PTEN hamartoma tumor syndrome/Cowden syndrome, DICER1 tumor-predisposition syndrome, PRKAR1A–Carney complex, and WRN–Werner syndrome. These are the most actionable germline findings. (capezzone2021familialnonmedullarythyroid pages 4-5, yang2016familialnonmedullarythyroid pages 2-4, sanchezares2022susceptibilitygenesand pages 1-2)
Nonsyndromic FNMTC: the commoner class, with complex monogenic, oligogenic, or polygenic susceptibility. Linkage regions include TCO/19p13.2, fPTC/PRN/1q21, NMTC1/2q21, MNG1, FTEN, 6q22, and 8q24. Candidate genes include FOXE1, SRGAP1, NKX2-1, HABP2, MAP2K5, SRRM2, DUOX2, PLCB1, BROX, POT1, ATM, CHEK2, NOP53, NDUFA13, TIMM44, ANXA3, NTN4, SERPINA1, FKBP10, PLEKHG5, P2RX5, and SAPCD1. Most associations are not sufficiently replicated for routine predictive testing. (yang2016familialnonmedullarythyroid pages 1-2, cirello2021clinicalandgenetic pages 2-3, kamani2022geneticsusceptibilityto pages 11-12)

Classic tumor drivers—BRAF, RAS, RET/PTC, NTRK, and PPARG rearrangements—are generally somatic rather than inherited FNMTC causes. Familial and sporadic tumors share these alterations. (capezzone2021familialnonmedullarythyroid pages 2-4, sanchezares2022susceptibilitygenesand pages 1-2)

Variant interpretation

HABP2 p.Gly534Glu (G534E): initially proposed as a dominant susceptibility allele, but subsequent studies found inconsistent segregation and association. It should not be treated as a universally pathogenic FNMTC variant. (capezzone2021familialnonmedullarythyroid pages 4-5, yang2016familialnonmedullarythyroid pages 13-14)
DUOX2 c.3607A>G, p.Tyr1203His: reported to co-segregate in one family and estimated as extremely rare—approximately 1/138,000—but absent from all 86 tested members of 33 independent Italian families. This is a family-level candidate, not a validated general cause. (cirello2021clinicalandgenetic pages 2-3, cirello2021clinicalandgenetic pages 1-2)
FOXE1: the strongest repeatedly supported common susceptibility locus, but largely a moderate/low-effect risk locus rather than a highly penetrant diagnostic gene. Reviews describe FOXE1 penetrance as moderate-to-high for selected variants, while many GWAS loci have odds ratios only around 1.2–1.8. (capezzone2021familialnonmedullarythyroid pages 2-4, kamani2022geneticsusceptibilityto pages 14-15, kamani2022geneticsusceptibilityto pages 15-16)
CHEK2, POT1, RET, TG, EWSR1 and other rare WGS candidates require segregation, population-frequency, functional, and independent-family validation before ACMG pathogenic classification. One WGS pipeline required MAF <0.1%, CADD-PHRED >10, family segregation, and predicted deleteriousness by ≥60% of in-silico tools; these filters prioritize candidates but do not establish pathogenicity. (srivastava2019wholegenomesequencing pages 5-7, srivastava2019wholegenomesequencing pages 2-5)

No robust disease-wide carrier frequency can be calculated because there is no single causal allele. Population frequency must be reported variant by variant using ancestry-matched gnomAD/TOPMed data at the time of clinical interpretation.

Environmental, lifestyle, and infectious factors

Family history is the defining risk factor. First-degree relatives have approximately 3-fold risk in a Swedish database analysis, 5.2–5.47-fold risk in another synthesis, and 8–10-fold risk in selected familial analyses; differences reflect case definitions, populations, and ascertainment. More than 90% of familial clusters contain only two affected members. (capezzone2021familialnonmedullarythyroid pages 2-4, capezzone2021familialnonmedullarythyroid pages 1-2, kamani2022geneticsusceptibilityto pages 1-2)

Ionizing radiation, especially childhood neck exposure, is an established risk factor for thyroid carcinoma generally and must be excluded as a shared explanation when classifying a nonsyndromic kindred. No FNMTC-specific quantitative gene–radiation interaction is established. Sex, age, iodine nutrition, obesity, and benign thyroid disease may alter background NMTC risk, but current evidence does not establish them as specific causes of familial clustering. There is no infectious cause and no demonstrated vaccine-preventable trigger. (sanchezares2022susceptibilitygenesand pages 1-2)

Protective factors and gene–environment interaction

No reproducible protective germline variant, diet, medication, or lifestyle intervention specifically prevents FNMTC. Avoiding unnecessary ionizing radiation is prudent general prevention, but does not eliminate inherited susceptibility. Evidence is insufficient to quantify specific gene–environment interactions. This is a major knowledge gap rather than evidence of no interaction.

3. Phenotypes

FNMTC can be asymptomatic until a nodule is detected. The clinical phenotype is otherwise that of differentiated thyroid carcinoma.

Thyroid nodule/mass: clinical sign or imaging finding; often insidious and painless. Benign nodules, follicular adenoma, and multinodular goiter commonly coexist. Suggested HPO: Thyroid nodule, Multinodular goiter. (NCT01109420 chunk 1, sanchezares2022susceptibilitygenesand pages 1-2)
Papillary thyroid carcinoma: malignant pathologic phenotype, usually classic or follicular variant; >85% of NMTC and 85–91% of familial tumors in summarized series. Suggested HPO: Thyroid carcinoma. (yang2016familialnonmedullarythyroid pages 1-2, kamani2022geneticsusceptibilityto pages 1-2)
Multifocal/bilateral carcinoma: pathologic sign, variably frequent and often cited as enriched in familial tumors. In one 43-patient familial series, 56% were multifocal. Suggested HPO: Multifocal neoplasm; bilateral thyroid involvement should be separately annotated. (capezzone2021familialnonmedullarythyroid pages 6-7, cirello2021clinicalandgenetic pages 3-4)
Extrathyroidal extension: locally invasive sign; 35% in the same series. Severity ranges from microscopic extension to invasion of neck structures. (cirello2021clinicalandgenetic pages 3-4)
Cervical lymph-node metastasis: regional metastatic sign; 26% in the Italian series. Suggested HPO: Lymph node metastasis. (cirello2021clinicalandgenetic pages 3-4)
Distant/lung metastasis: advanced manifestation; lung metastases occurred in 7% of that series. Suggested HPO: Pulmonary metastasis. (cirello2021clinicalandgenetic pages 3-4)
Hashimoto thyroiditis association: reported more often in some familial pathology series, but its causal role and frequency are uncertain. (sanchezares2022susceptibilitygenesand pages 1-2)

Age and severity are variable. One clinical cohort had median diagnosis at 44 years, range 8–81 years. Reviews report younger presentation and possible anticipation, but ascertainment and intensified surveillance can produce apparent anticipation. (cirello2021clinicalandgenetic pages 3-4, kamani2022geneticsusceptibilityto pages 2-4)

Quality-of-life effects are primarily those of thyroid cancer and treatment: fear of recurrence, repeated neck imaging and laboratory surveillance, lifelong levothyroxine after total thyroidectomy, and possible hypoparathyroidism, voice impairment, or treatment-related fatigue. Retrieved evidence did not provide validated FNMTC-specific EQ-5D, SF-36, or PROMIS estimates; extrapolation from sporadic differentiated thyroid cancer should be labeled indirect.

4. Genetic and molecular information

Inheritance, penetrance, and expressivity

Nonsyndromic families often appear autosomal dominant, but with incomplete, age-dependent penetrance and marked variable expressivity; polygenic inheritance remains plausible. There is no established role for recessive inheritance, mitochondrial transmission, repeat expansion, germline mosaicism, or consanguinity in typical FNMTC. Founder effects may exist for individual variants but are not a general feature. (capezzone2021familialnonmedullarythyroid pages 2-4, capezzone2021familialnonmedullarythyroid pages 4-5)

Clinical anticipation has been reported, with second generations presenting younger and sometimes more severely. It is not proven to represent a repeat-expansion mechanism; surveillance bias and changing diagnostic intensity are important alternatives. (yang2016familialnonmedullarythyroid pages 1-2, kamani2022geneticsusceptibilityto pages 2-4)

Epigenetic and telomere findings

Shorter telomere length and imbalance of the telomere–telomerase system have been reported in familial cases and may modify susceptibility. Differential activity of miR-886-3p and miR-20a has also been proposed. These remain research biomarkers, not validated diagnostic tests. No reproducible FNMTC-specific methylation or histone-modification signature is ready for clinical use. (capezzone2021familialnonmedullarythyroid pages 4-5, cirello2021clinicalandgenetic pages 2-3, yang2016familialnonmedullarythyroid pages 13-14)

Chromosomal abnormalities

Historical linkage regions are susceptibility intervals, not recurrent diagnostic structural variants. Tumor translocations such as RET/PTC and NTRK fusions can occur somatically. Routine constitutional karyotyping, FISH, or chromosomal microarray has low expected yield in isolated FNMTC unless additional congenital or syndromic features suggest a chromosome disorder. (yang2016familialnonmedullarythyroid pages 1-2, cirello2021clinicalandgenetic pages 3-4)

5. Environmental information

No toxin, occupational exposure, lifestyle pattern, or pathogen uniquely defines FNMTC. Shared radiation exposure must be considered in clustered families. Smoking and alcohol are not established FNMTC-specific factors; thyroid-cancer associations with body mass, diet, iodine status, and endocrine-disrupting chemicals remain general epidemiologic issues, not demonstrated explanations for familial transmission. Environmental annotations should therefore be represented as general thyroid-cancer modifiers with low disease specificity, not as confirmed FNMTC causes.

6. Mechanism and pathophysiology

Causal chain

A defensible current model is:

Inherited susceptibility—a high-penetrance syndromic defect or a family-specific combination of rare and common alleles—→ altered genome maintenance, developmental transcription, growth-factor signaling, telomere biology, or miRNA regulation → increased probability of acquiring somatic thyroid drivers → constitutive MAPK/ERK and/or PI3K/AKT signaling in thyroid follicular cells → proliferation, survival, clonal expansion, papillary/follicular carcinoma → multifocal local growth, cervical nodal spread, and occasionally distant metastasis. (srivastava2019wholegenomesequencing pages 5-7, srivastava2019wholegenomesequencing pages 19-21, sanchezares2022susceptibilitygenesand pages 1-2)

Upstream mechanisms depend on the syndrome: PTEN loss releases PI3K–AKT signaling; APC disruption alters Wnt/β-catenin regulation; DICER1 defects impair miRNA processing; PRKAR1A defects dysregulate cAMP–PKA signaling; WRN loss impairs DNA repair and genome stability. In nonsyndromic disease, pathway convergence is clearer than any shared initiating gene.

Genomic and molecular profiling

WGS of 23 affected and three unaffected individuals from five families reduced 91,427–207,873 raw variants per family to 31 prioritized coding and 39 regulatory-region candidates. Among 210 pathway-mappable genes, receptor-tyrosine-kinase and GPCR networks converged on MAPK/ERK and PI3K/AKT; AKT and ERK1/2 were network hubs. Thyroid cancer enrichment was statistically significant but ranked below many broad cancer functions, underscoring that pathway analysis is hypothesis-generating. (srivastava2019wholegenomesequencing pages 5-7, srivastava2019wholegenomesequencing pages 2-5, srivastava2019wholegenomesequencing pages 16-19, srivastava2019wholegenomesequencing pages 19-21)

Tumor profiling in a familial series assayed BRAF V600E, RAS, AKT1, PIK3CA, EIF1AX, TERT-promoter hotspots and RET/PTC/NTRK fusions. Familial and sporadic NMTC share morphology and somatic drivers; currently, the same molecularly matched therapies apply. (cirello2021clinicalandgenetic pages 3-4, sanchezares2022susceptibilitygenesand pages 1-2)

No validated FNMTC-specific transcriptomic, proteomic, metabolomic, lipidomic, single-cell, spatial-transcriptomic, or integrated multi-omic signature was identified. These technologies are active in thyroid-cancer research, but familial status has not yet yielded a reproducible clinical classifier.

Ontology suggestions

Cell type: thyroid follicular cell, CL:0000501.
Anatomy: thyroid gland, UBERON:0002046; cervical lymph nodes and lung for metastatic sites.
Processes: MAPK cascade, GO:0000165; cell population proliferation, GO:0008283; PI3K–AKT signaling, DNA-damage response, miRNA processing, telomere maintenance, apoptotic signaling, and cell migration.
Subcellular sites: nucleus for transcription/DNA repair/telomeres; plasma membrane and cytosol for RTK–RAS–MAPK and PI3K–AKT signaling; no FNMTC-specific organelle lesion is established.

7. Anatomical structures affected

The primary organ is the thyroid gland, specifically follicular epithelium rather than calcitonin-producing parafollicular C cells. Tumors may be unilateral or bilateral and unifocal or multifocal. Regional disease involves the central and lateral cervical lymph nodes; advanced disease may affect lung, bone, or other distant sites. The endocrine system is primary; respiratory, skeletal, and neurologic systems are involved only through local invasion, metastasis, or treatment complications. (capezzone2021familialnonmedullarythyroid pages 6-7, cirello2021clinicalandgenetic pages 3-4)

At the tissue level, affected structures include thyroid follicles, papillary tumor epithelium, tumor stroma, lymphatic vessels, and metastatic lymph-node parenchyma. Relevant GO cellular compartments include nucleus, chromosome/telomere, cytoplasm, plasma membrane, and receptor-signaling complexes.

8. Temporal development

Onset is typically insidious and adult, but pediatric and geriatric presentations occur; the documented 8–81-year range demonstrates marked age variability. Earlier onset should increase suspicion of inherited susceptibility, particularly with multicentricity or bilaterality. (capezzone2021familialnonmedullarythyroid pages 6-7, cirello2021clinicalandgenetic pages 3-4)

Course follows differentiated thyroid-cancer staging rather than a separate FNMTC staging system: localized intrathyroidal tumor → regional nodal disease → locally invasive or distant metastatic disease. Many PTCs are indolent, although familial cohorts can show more adverse features at diagnosis. Treatment-induced remission is common; biochemical or structural persistence/recurrence can occur. No credible spontaneous-remission pattern is established.

The critical intervention window is before clinically consequential nodal or distant spread, but overdiagnosis of indolent microcarcinoma is a countervailing harm. That balance explains disagreement over ultrasound screening.

9. Inheritance and population

FNMTC accounts for approximately 3–9%, nearly 10%, or 5–15% of thyroid/NMTC cases across reviews; variation reflects definition and denominator. Syndromic cases account for about 5% of familial disease, leaving approximately 95% classified as nonsyndromic. FNMTC-specific incidence per 100,000 is not reliably established. (yang2016familialnonmedullarythyroid pages 1-2, capezzone2021familialnonmedullarythyroid pages 1-2, kamani2022geneticsusceptibilityto pages 1-2)

Women predominate, as in sporadic differentiated thyroid cancer. In one familial clinical series, 38/43 patients (88%) were female and five male. This does not establish a universal sex ratio because of referral and family ascertainment. (cirello2021clinicalandgenetic pages 3-4)

No ethnicity is uniquely affected. GWAS effect sizes and rare-variant frequencies differ by ancestry, making ancestry-matched controls essential. No general carrier frequency is meaningful for a genetically heterogeneous trait.

10. Diagnostics

Clinical evaluation

Diagnosis begins with a three-generation pedigree, pathology confirmation in affected relatives, assessment of radiation exposure, and examination for syndromic features. Neck ultrasonography characterizes thyroid nodules and cervical lymph nodes. Suspicious nodules undergo ultrasound-guided fine-needle aspiration; cytology is classified using standard thyroid systems, with molecular testing used for indeterminate nodules where clinically appropriate. Serum TSH guides nodule evaluation but neither TSH nor thyroglobulin diagnoses FNMTC. Post-treatment thyroglobulin and anti-thyroglobulin antibodies are surveillance biomarkers.

Histopathology establishes papillary, follicular, or oncocytic carcinoma and documents multifocality, bilaterality, vascular/capsular invasion, extrathyroidal extension, margins, and nodal status. FNMTC and sporadic tumors cannot usually be distinguished morphologically or by common somatic mutations alone. (cirello2021clinicalandgenetic pages 3-4, sanchezares2022susceptibilitygenesand pages 1-2)

Genetic testing strategy

If syndromic features are present: use phenotype-directed germline testing—e.g., APC, PTEN, DICER1, PRKAR1A, WRN—with deletion/duplication analysis where appropriate. A multigene hereditary-cancer panel can be efficient when phenotypes overlap. (yang2016familialnonmedullarythyroid pages 2-4, sanchezares2022susceptibilitygenesand pages 1-2)
If apparently isolated nonsyndromic FNMTC: pre-test counseling should explain that no validated routine predictive panel explains most families. WES/WGS is most appropriate in research or carefully selected ≥3-case families, ideally sequencing multiple affected and unaffected relatives with segregation analysis. (yang2016familialnonmedullarythyroid pages 13-14, srivastava2019wholegenomesequencing pages 2-5, kamani2022geneticsusceptibilityto pages 14-15)
CMA, karyotype, FISH, mitochondrial sequencing, and repeat-expansion testing: not routine unless another phenotype supplies an independent indication.
Tumor sequencing/liquid biopsy: useful for therapy selection in advanced disease, not for proving familial causation. A tumor variant requires matched normal testing before it can be called germline.

Clinical criteria and differential diagnosis

Two first-degree relatives meet the conventional definition, but three affected relatives provide much greater specificity. Differential diagnoses include sporadic coincidental PTC; medullary thyroid carcinoma/MEN2; radiation-associated thyroid cancer; metastasis to thyroid; and syndromic NMTC due to PTEN, APC, DICER1, PRKAR1A, WRN, or other cancer syndromes. (yang2016familialnonmedullarythyroid pages 13-14, sanchezares2022susceptibilitygenesand pages 1-2)

11. Outcomes and prognosis

Whether FNMTC is intrinsically more aggressive remains unresolved. Some studies report younger age, larger or multifocal tumors, more extrathyroidal extension, nodal metastases, recurrence, and reduced survival; matched studies find little difference. The Italian series found a significantly more aggressive presentation but not a worse outcome after appropriate treatment. Reviews likewise report no consistent mortality or recurrence difference. (yang2016familialnonmedullarythyroid pages 1-2, capezzone2021familialnonmedullarythyroid pages 1-2, cirello2021clinicalandgenetic pages 1-2, kamani2022geneticsusceptibilityto pages 1-2)

Accordingly, no reliable FNMTC-specific 5- or 10-year survival estimate can be supplied from the retrieved evidence. Prognosis should use standard differentiated-thyroid-cancer variables: age, histologic subtype, tumor size, gross extrathyroidal extension, completeness of resection, nodal burden, distant metastasis, radioiodine avidity, thyroglobulin response, and actionable somatic genotype. Family history alone is not a validated basis for assigning a worse stage.

Long-term morbidity is more commonly treatment-related or surveillance-related than disabling tumor burden: hypothyroidism, hypoparathyroidism, recurrent-laryngeal-nerve injury, neck discomfort, salivary effects from radioiodine, anxiety, and financial/psychosocial burden. FNMTC-specific disability and quality-of-life statistics remain insufficient.

12. Treatment and applications

FNMTC is treated according to standard differentiated thyroid-cancer risk stratification. Current ATA-aligned reviews do not recommend a different therapeutic approach solely because of family history. (capezzone2021familialnonmedullarythyroid pages 6-7)

Surgery: lobectomy or total thyroidectomy according to tumor size, bilaterality/multifocality, nodal disease, molecular/pathologic risk, and patient preference; therapeutic compartment-oriented neck dissection for proven nodal metastases. In one referral series, 93% underwent total thyroidectomy, but this is not evidence that all FNMTC requires total thyroidectomy. Suggested NCIT: Thyroidectomy, Lobectomy, Neck Dissection. (cirello2021clinicalandgenetic pages 3-4)
Radioactive iodine (I-131): selected after surgery according to recurrence risk and radioiodine avidity, not automatically for familial status. Suggested NCIT: Radioactive Iodine Therapy; CHEBI annotation should use the curated iodide/I-131 entity.
Levothyroxine/TSH suppression: replacement after total thyroidectomy and risk-adapted TSH suppression. Suggested NCIT: Thyroid Hormone Replacement Therapy, TSH Suppression Therapy.
Advanced radioiodine-refractory disease: molecularly selected kinase inhibition follows ordinary DTC practice—RET or NTRK inhibitors for corresponding fusions, BRAF/MEK-directed approaches in appropriate BRAF-altered disease, and multikinase inhibitors for progressive refractory disease. Familial and sporadic tumors currently share these therapeutic rules because their somatic drivers overlap. Suggested NCIT: Kinase Inhibitor Therapy, Targeted Therapy. (sanchezares2022susceptibilitygenesand pages 1-2)
Immunotherapy, gene therapy, cell therapy, RNA therapy, or prophylactic thyroidectomy: no FNMTC-specific approved indication. Prophylactic thyroidectomy is not recommended for nonsyndromic FNMTC in the manner used for RET-positive MEN2.

There is no established FNMTC pharmacogenomic rule. Somatic genotype guides targeted efficacy; germline findings primarily guide syndrome surveillance rather than drug metabolism.

13. Prevention and screening

Primary prevention

No intervention can remove inherited susceptibility. Avoid unnecessary childhood neck radiation and manage general health risks, but no diet, vaccine, supplement, or prophylactic drug has demonstrated FNMTC prevention.

Secondary prevention

Routine population ultrasound screening is not recommended. Universal ultrasound screening of all relatives is also controversial: one prospective study found thyroid cancer in 4.6% of screened at-risk relatives from two-case families, approximately comparable to detection in heavily imaged populations. Major reviews report that ATA, NCCN, and ESMO have not endorsed routine genetic screening of nonsyndromic relatives because evidence is insufficient. (capezzone2021familialnonmedullarythyroid pages 4-5, kamani2022geneticsusceptibilityto pages 2-4, kamani2022geneticsusceptibilityto pages 14-15)

A reasonable expert approach is individualized counseling and clinical neck examination, with lower threshold for ultrasound in families with ≥3 affected members, unusually young onset, aggressive disease, palpable abnormalities, or a known syndrome. Families with only two older-onset micro-PTCs carry substantial risk of coincidental clustering and overdiagnosis. (yang2016familialnonmedullarythyroid pages 13-14, capezzone2021familialnonmedullarythyroid pages 6-7)

Real-world implementation

The NIDDK prospective observational cohort NCT01109420, “Clinical and Genetic Studies in Familial Non-medullary Thyroid Cancer,” began August 12, 2010 and was listed as recruiting with estimated enrollment of 500. It accepts affected families and unaffected relatives, performs family history, examination, laboratory testing and imaging, and annually re-screens unaffected participants without malignant tumors. Objectives include defining natural history, optimizing screening, and identifying susceptibility genes. ClinicalTrials.gov: NCT01109420. (NCT01109420 chunk 1)

Tertiary prevention and counseling

Risk-adapted postoperative surveillance, thyroglobulin monitoring, cervical ultrasound, appropriate radioiodine use, and treatment of persistent/recurrent disease prevent complications. Genetic counseling should address uncertain penetrance, limitations of negative testing, possible incidental findings, and syndrome-specific cancer surveillance. Reproductive testing or preimplantation genetic testing is technically meaningful only when a clearly pathogenic germline variant has been established; it is not appropriate for an unvalidated candidate allele.

14. Other species and natural disease

Spontaneous follicular-cell-derived thyroid tumors occur in companion and laboratory animals, but the retrieved literature did not establish a naturally occurring veterinary syndrome orthologous to human nonsyndromic FNMTC. There is no zoonotic transmission. Human susceptibility genes have conserved orthologs in mouse and other vertebrates, but conservation of a pathway does not establish a homologous familial disease.

Suggested taxonomy annotations for general comparative research include Homo sapiens (NCBI Taxon 9606), Mus musculus (10090), Rattus norvegicus (10116), and Danio rerio (7955). Breed-specific VBO annotations are not supported for FNMTC.

15. Model organisms

No single model faithfully reproduces genetically heterogeneous nonsyndromic FNMTC. Available thyroid-cancer models instead interrogate downstream mechanisms:

genetically engineered mice expressing thyroid-specific BRAF V600E, RET/PTC, RAS, or altered PTEN/PI3K signaling;
thyroid cancer cell lines and patient-derived cultures/organoids;
xenograft or patient-derived xenograft models;
CRISPR knock-in/knockout systems for candidate variants;
zebrafish models for thyroid development and oncogenic signaling.

These models can reproduce follicular-cell transformation and MAPK/PI3K pathway activation, but generally model a somatic driver or one syndrome—not the incomplete penetrance, polygenic architecture, and within-family variability of human FNMTC. The most informative future design would combine a segregating human germline variant with a thyroid-specific somatic driver and longitudinal assessment of penetrance.

Recent developments and evidence limitations

The requested 2023–2024 priority yielded limited directly retrievable primary literature. A 2024 report proposed PAK4 as a susceptibility gene (DOI 10.1089/thy.2023.0564), but full evidence was unavailable in the retrieved corpus; it should therefore be treated as emerging, not yet independently validated, and not assigned as an established causal gene. The strongest accessible contemporary syntheses were published in 2021–2022, while the ongoing NIH cohort supplies current implementation data.

Three overarching limitations should be retained in the knowledge base: (1) two-case families are contaminated by coincidental sporadic PTC; (2) many candidate-gene reports are single-family or underpowered and lack replication; and (3) screening changes apparent age, tumor size, and aggressiveness. Consequently, reported anticipation, penetrance, and familial–sporadic outcome differences should be annotated with ascertainment-bias qualifiers.

Key sources and direct abstract quotations

Capezzone et al., Journal of Endocrinological Investigation, published online October 2020/volume 2021, DOI 10.1007/s40618-020-01435-x: “FNMTC is described as a polygenic disorder associated with multiple low- to moderate-penetrance susceptibility genes and incomplete penetrance.” (capezzone2021familialnonmedullarythyroid pages 1-2)
Cirello et al., Frontiers in Endocrinology, January 2021, DOI 10.3389/fendo.2020.589340: “Familial tumors had a statistically significant more aggressive presentation at diagnosis, though not resulting in a worst outcome.” (cirello2021clinicalandgenetic pages 1-2)
Sánchez-Ares et al., Frontiers in Endocrinology, February 2022, DOI 10.3389/fendo.2022.829103: “Non-syndromic familial non-medullary carcinoma has a complex and heterogeneous genetic basis involving several genes and loci with a monogenic or polygenic inheritance model.” (sanchezares2022susceptibilitygenesand pages 1-2)
Kamani et al., Hereditary Cancer in Clinical Practice, March 2022, DOI 10.1186/s13053-022-00215-3: “The gene(s) responsible for the vast majority of non-syndromic FNMTC cases are yet to be identified.” (kamani2022geneticsusceptibilityto pages 1-2)

PMIDs were not exposed in the retrieved full-text metadata and therefore are not fabricated here. DOI links provide stable source resolution. The evidence base supports robust disease-level characterization, but not definitive assignment of most nonsyndromic candidate genes as pathogenic.

References

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(capezzone2021familialnonmedullarythyroid pages 4-5): M. Capezzone, E. Robenshtok, E. Robenshtok, S. Cantara, and M. G. Castagna. Familial non-medullary thyroid cancer: a critical review. Journal of Endocrinological Investigation, 44:943-950, Oct 2021. URL: https://doi.org/10.1007/s40618-020-01435-x, doi:10.1007/s40618-020-01435-x. This article has 81 citations and is from a peer-reviewed journal.
(kamani2022geneticsusceptibilityto pages 11-12): Tina Kamani, Parsa Charkhchi, Afshan Zahedi, and Mohammad R. Akbari. Genetic susceptibility to hereditary non-medullary thyroid cancer. Hereditary Cancer in Clinical Practice, Mar 2022. URL: https://doi.org/10.1186/s13053-022-00215-3, doi:10.1186/s13053-022-00215-3. This article has 37 citations and is from a peer-reviewed journal.
(yang2016familialnonmedullarythyroid pages 1-2): Samantha Peiling Yang and Joanne Ngeow. Familial non-medullary thyroid cancer: unraveling the genetic maze. Endocrine-related cancer, 23 12:R577-R595, Dec 2016. URL: https://doi.org/10.1530/erc-16-0067, doi:10.1530/erc-16-0067. This article has 140 citations and is from a domain leading peer-reviewed journal.
(capezzone2021familialnonmedullarythyroid pages 1-2): M. Capezzone, E. Robenshtok, E. Robenshtok, S. Cantara, and M. G. Castagna. Familial non-medullary thyroid cancer: a critical review. Journal of Endocrinological Investigation, 44:943-950, Oct 2021. URL: https://doi.org/10.1007/s40618-020-01435-x, doi:10.1007/s40618-020-01435-x. This article has 81 citations and is from a peer-reviewed journal.
(NCT01109420 chunk 1): Clinical and Genetic Studies in Familial Non-medullary Thyroid Cancer. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). 2010. ClinicalTrials.gov Identifier: NCT01109420
(cirello2021clinicalandgenetic pages 3-4): Valentina Cirello, Carla Colombo, Olga Karapanou, Gabriele Pogliaghi, Luca Persani, and Laura Fugazzola. Clinical and genetic features of a large monocentric series of familial non-medullary thyroid cancers. Frontiers in Endocrinology, Jan 2021. URL: https://doi.org/10.3389/fendo.2020.589340, doi:10.3389/fendo.2020.589340. This article has 10 citations.
(cirello2021clinicalandgenetic pages 1-2): Valentina Cirello, Carla Colombo, Olga Karapanou, Gabriele Pogliaghi, Luca Persani, and Laura Fugazzola. Clinical and genetic features of a large monocentric series of familial non-medullary thyroid cancers. Frontiers in Endocrinology, Jan 2021. URL: https://doi.org/10.3389/fendo.2020.589340, doi:10.3389/fendo.2020.589340. This article has 10 citations.
(srivastava2019wholegenomesequencing pages 5-7): Aayushi Srivastava, Abhishek Kumar, Sara Giangiobbe, Elena Bonora, Kari Hemminki, Asta Försti, and Obul Reddy Bandapalli. Whole genome sequencing of familial non-medullary thyroid cancer identifies germline alterations in mapk/erk and pi3k/akt signaling pathways. ArXiv, Oct 2019. URL: https://doi.org/10.20944/preprints201910.0154.v1, doi:10.20944/preprints201910.0154.v1. This article has 34 citations.
(srivastava2019wholegenomesequencing pages 19-21): Aayushi Srivastava, Abhishek Kumar, Sara Giangiobbe, Elena Bonora, Kari Hemminki, Asta Försti, and Obul Reddy Bandapalli. Whole genome sequencing of familial non-medullary thyroid cancer identifies germline alterations in mapk/erk and pi3k/akt signaling pathways. ArXiv, Oct 2019. URL: https://doi.org/10.20944/preprints201910.0154.v1, doi:10.20944/preprints201910.0154.v1. This article has 34 citations.
(yang2016familialnonmedullarythyroid pages 2-4): Samantha Peiling Yang and Joanne Ngeow. Familial non-medullary thyroid cancer: unraveling the genetic maze. Endocrine-related cancer, 23 12:R577-R595, Dec 2016. URL: https://doi.org/10.1530/erc-16-0067, doi:10.1530/erc-16-0067. This article has 140 citations and is from a domain leading peer-reviewed journal.
(capezzone2021familialnonmedullarythyroid pages 6-7): M. Capezzone, E. Robenshtok, E. Robenshtok, S. Cantara, and M. G. Castagna. Familial non-medullary thyroid cancer: a critical review. Journal of Endocrinological Investigation, 44:943-950, Oct 2021. URL: https://doi.org/10.1007/s40618-020-01435-x, doi:10.1007/s40618-020-01435-x. This article has 81 citations and is from a peer-reviewed journal.
(kamani2022geneticsusceptibilityto pages 14-15): Tina Kamani, Parsa Charkhchi, Afshan Zahedi, and Mohammad R. Akbari. Genetic susceptibility to hereditary non-medullary thyroid cancer. Hereditary Cancer in Clinical Practice, Mar 2022. URL: https://doi.org/10.1186/s13053-022-00215-3, doi:10.1186/s13053-022-00215-3. This article has 37 citations and is from a peer-reviewed journal.
(srivastava2019wholegenomesequencing pages 2-5): Aayushi Srivastava, Abhishek Kumar, Sara Giangiobbe, Elena Bonora, Kari Hemminki, Asta Försti, and Obul Reddy Bandapalli. Whole genome sequencing of familial non-medullary thyroid cancer identifies germline alterations in mapk/erk and pi3k/akt signaling pathways. ArXiv, Oct 2019. URL: https://doi.org/10.20944/preprints201910.0154.v1, doi:10.20944/preprints201910.0154.v1. This article has 34 citations.
(cirello2021clinicalandgenetic pages 2-3): Valentina Cirello, Carla Colombo, Olga Karapanou, Gabriele Pogliaghi, Luca Persani, and Laura Fugazzola. Clinical and genetic features of a large monocentric series of familial non-medullary thyroid cancers. Frontiers in Endocrinology, Jan 2021. URL: https://doi.org/10.3389/fendo.2020.589340, doi:10.3389/fendo.2020.589340. This article has 10 citations.
(kamani2022geneticsusceptibilityto pages 15-16): Tina Kamani, Parsa Charkhchi, Afshan Zahedi, and Mohammad R. Akbari. Genetic susceptibility to hereditary non-medullary thyroid cancer. Hereditary Cancer in Clinical Practice, Mar 2022. URL: https://doi.org/10.1186/s13053-022-00215-3, doi:10.1186/s13053-022-00215-3. This article has 37 citations and is from a peer-reviewed journal.
(kamani2022geneticsusceptibilityto pages 2-4): Tina Kamani, Parsa Charkhchi, Afshan Zahedi, and Mohammad R. Akbari. Genetic susceptibility to hereditary non-medullary thyroid cancer. Hereditary Cancer in Clinical Practice, Mar 2022. URL: https://doi.org/10.1186/s13053-022-00215-3, doi:10.1186/s13053-022-00215-3. This article has 37 citations and is from a peer-reviewed journal.
(srivastava2019wholegenomesequencing pages 16-19): Aayushi Srivastava, Abhishek Kumar, Sara Giangiobbe, Elena Bonora, Kari Hemminki, Asta Försti, and Obul Reddy Bandapalli. Whole genome sequencing of familial non-medullary thyroid cancer identifies germline alterations in mapk/erk and pi3k/akt signaling pathways. ArXiv, Oct 2019. URL: https://doi.org/10.20944/preprints201910.0154.v1, doi:10.20944/preprints201910.0154.v1. This article has 34 citations.

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Familial Nonmedullary Thyroid Carcinoma: Disease-Characteristics Report

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