Congenital Hypothyroidism

Complex MONDO:0018612 Pathograph 28 Show in embeddings browser hypothyroidism

Congenital hypothyroidism is thyroid hormone deficiency present at birth and is one of the most common preventable causes of intellectual disability worldwide. The primary form, caused by thyroid dysgenesis or dyshormonogenesis, accounts for the vast majority of cases with an incidence of 1 in 2000 to 1 in 3000. Universal newborn screening enables early detection and treatment with levothyroxine, which prevents irreversible neurodevelopmental damage when initiated within the first two weeks of life.

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3
Inheritance
6
Pathophys.
13
Phenotypes
28
Pathograph
12
Genes
3
Medical Actions
13
Subtypes
2
Datasets
1
Models
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Deep Research
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Inheritance

3
Autosomal recessive inheritance HP:0000007
Dyshormonogenesis subtypes (TPO, TG, DUOX2, DUOXA2, SLC5A5, SLC26A4, IYD mutations) follow autosomal recessive inheritance with 25% recurrence risk.
Autosomal recessive inheritance
Show evidence (2 references)
PMID:29650690 SUPPORT Human Clinical
"Autosomal recessive inheritance of CH caused by mutations in DUOX2, DUOXA2, TG and TPO was confirmed by analysis of 22 family pedigrees."
Family pedigree analysis confirms autosomal recessive inheritance for dyshormonogenesis genes.
PMID:33272083 SUPPORT Human Clinical
"Counseling should include explaining inheritance and the risk of recurrence of the patient's primary or central form of CH, based on the CH subtype, the family history, and, if known, the (genetic) cause"
Guidelines recommend counseling on inheritance including recurrence risk for autosomal recessive forms.
Digenic (thyroid dysgenesis) HP:0010984
Thyroid dysgenesis, long treated as sporadic, has a digenic arm. In a prospective nationwide French cohort of 514 screened newborns, 16 of 292 genotyped patients (5.5%) each carried a variant in a thyroid DEVELOPMENT gene together with a variant in the H2O2-generation complex gene DUOX2 or DUOXA2. The pairing is not two arbitrary thyroid genes: one lesion impairs gland formation and the other impairs hormone synthesis in the gland that does form, and the study supported the model with familial segregation and in vitro cell-migration assays rather than co-occurrence alone. Note the scale: the digenic yield (16/292, 5.5%) nearly matched the monogenic yield (20/292, 6.8%) in the same cohort, so within CHTD this is not a rare curiosity at the edge of a mostly monogenic disease. Contributing loci: a thyroid development gene (the panel's CHTD set) plus DUOX2 or DUOXA2, all of which are already recorded in the genetic section; the DUOX2 and DUOXA2 records also appear under the recessive dyshormonogenesis block above, which is the point - the same locus behaves differently depending on what it is paired with.
Digenic inheritance
Show evidence (2 references)
PMID:39787321 SUPPORT Human Clinical
"We found a digenic mode of inheritance in 16 (5.5%) patients, each carrying a variant in a thyroid development gene and a variant in the H2O2 generation complex gene DUOX2/DUOXA2."
Quantifies the digenic arm in a prospective nationwide screened cohort and names the two gene classes that pair.
PMID:39787321 SUPPORT Human Clinical
"Familial segregation analysis and in vitro functional studies supported this model."
Records the corroboration that raises this above an observation of two variants in the same exome. Tagged HUMAN_CLINICAL for the familial segregation, which is the arm this entry relies on; the sentence also refers to the study's in vitro cell-migration assays, and cannot be split without breaking the quote.
Sporadic occurrence
Thyroid dysgenesis, the most common cause of primary CH, is typically sporadic with unclear inheritance. Monogenic, polygenic, and multifactorial inheritance have all been proposed.
Show evidence (1 reference)
PMID:29650690 SUPPORT Human Clinical
"eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead to thyroid dysgenesis were identified in eight probands. These mutations were heterozygous in all cases and hypothyroidism was not observed in parents of these probands."
Heterozygous mutations in thyroid dysgenesis genes with unaffected parents suggest complex or sporadic rather than simple dominant inheritance.
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Subtypes

13
General
Permanent Primary Congenital Hypothyroidism MONDO:0016408
Permanent thyroid hormone deficiency due to thyroid gland dysgenesis (agenesis, ectopy, hypoplasia) or dyshormonogenesis, requiring lifelong levothyroxine replacement. Thyroid dysgenesis accounts for 65-85% of primary CH cases.
  • TSHR Resistance
  • CHNG2
  • CHNG5
  • Dyshormonogenesis
Transient Congenital Hypothyroidism MONDO:0015792
Temporary thyroid hormone deficiency at birth that resolves spontaneously, commonly due to maternal antithyroid antibodies, iodine excess or deficiency, or prematurity.
Central Congenital Hypothyroidism MONDO:0016410
Congenital thyroid hormone deficiency caused by insufficient hypothalamic or pituitary stimulation of the thyroid gland, with low free T4 and non-elevated TSH. Incidence approximately 1 in 16,000.
Familial Thyroid Dyshormonogenesis MONDO:0010132
Autosomal recessive defects in thyroid hormone synthesis enzymes and transporters (TPO, TG, DUOX2, DUOXA2, SLC5A5, SLC26A4) plus the iodide salvage enzyme IYD, causing goitrous congenital hypothyroidism.
  • TDH1
  • TDH2A
  • TDH3
  • TDH4
  • TDH5
  • TDH6
molecular etiology
TSH resistance due to TSHR loss of function MONDO:0010142
TSHR hgnc:12373 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in TSHR (hgnc:12373). hgnc:12373 is a gene from the HUGO Gene Nomenclature Committee.
Primary congenital hypothyroidism caused by loss-of-function variants in the TSH receptor, which leave follicular cells hyporesponsive to TSH. MONDO names the subtype after the receptor rather than after a gland malformation.
Show evidence (1 reference)
PMID:41303336 SUPPORT Human Clinical
"Mutations in ten genes involved in thyroid gland development during embryogenesis, TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have been identified in cohorts of patients with thyroid dysgenesis."
Lists TSHR among the genes in which mutations have been identified in thyroid dysgenesis cohorts.
Congenital nongoitrous hypothyroidism 2 (PAX8) MONDO:0024264
PAX8 hgnc:8622 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in PAX8 (hgnc:8622). hgnc:8622 is a gene from the HUGO Gene Nomenclature Committee.
Primary congenital hypothyroidism caused by PAX8 variants. PAX8 is one of the thyroid transcription factor genes in which mutations have been identified in cohorts of patients with thyroid dysgenesis.
Show evidence (1 reference)
PMID:29650690 SUPPORT Human Clinical
"eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead to thyroid dysgenesis were identified in eight probands."
Identifies PAX8 mutations in probands with thyroid dysgenesis in a Chinese cohort.
Congenital nongoitrous hypothyroidism 5 (NKX2-5) MONDO:0009154
NKX2-5 hgnc:2488 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in NKX2-5 (hgnc:2488). hgnc:2488 is a gene from the HUGO Gene Nomenclature Committee.
MONDO assigns this term to NKX2-5, a transcription factor whose main role is in heart development. The evidence is contested and this subtype is recorded as a candidate rather than an established one: the original report found three heterozygous missense changes in four of 241 patients with thyroid dysgenesis and described the role as previously unknown, while a later screen of 63 Brazilian children with thyroid dysgenesis found no mutations in NKX2-5 or in the other candidate genes it examined.
Show evidence (3 references)
PMID:16418214 SUPPORT Human Clinical
"NKX2-5 mutational screening in 241 patients with TD allowed the identification of three heterozygous missense changes (R25C, A119S, and R161P) in four patients with TD."
The primary human genetic evidence for this subtype, and the source of the yield quoted in its description.
PMID:16418214 SUPPORT Model Organism
"Our results indicate that Nkx2-5(-/-) embryos exhibit thyroid bud hypoplasia, providing evidence that NKX2-5 plays a role in thyroid organogenesis and that NKX2-5 mutations contribute to TD."
Mouse evidence that NKX2-5 acts in thyroid organogenesis, offered by the same study in support of the human finding.
PMID:30304112 REFUTE Human Clinical
"No mutations were detected in any of the candidate genes."
A negative screen of NKX2-5 in 63 children with thyroid dysgenesis. It does not exclude NKX2-5 as a cause in individual families, but it counts against treating it as an established contributor, which is why this subtype is recorded as a candidate.
Thyroid dyshormonogenesis 1 (SLC5A5, iodide transport defect) MONDO:0020716
SLC5A5 hgnc:11040 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in SLC5A5 (hgnc:11040). hgnc:11040 is a gene from the HUGO Gene Nomenclature Committee.
Dyshormonogenetic congenital hypothyroidism caused by biallelic SLC5A5 variants. SLC5A5 encodes the sodium/iodide symporter, the basolateral transporter of the two-step iodide transport route, so the defect is at the entry of iodide into the follicular cell.
Show evidence (2 references)
PMID:28648508 SUPPORT REVIEW SYNTHESIS Human Clinical
"TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes."
Names SLC5A5 among the genes in which mutations cause thyroid dyshormonogenesis.
PMID:28648508 SUPPORT BACKGROUND Other
"The iodide transport is a two-step process involving transporters located either in the basolateral or apical membranes, sodium iodide symporter (NIS) and pendrin (PDS), respectively."
Source for placing SLC5A5 at the basolateral uptake step, stated as established physiology rather than as a result of this review.
Thyroid dyshormonogenesis 2A (TPO) MONDO:0010133
TPO hgnc:12015 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in TPO (hgnc:12015). hgnc:12015 is a gene from the HUGO Gene Nomenclature Committee.
Dyshormonogenetic congenital hypothyroidism caused by biallelic TPO variants. Thyroid peroxidase is one of the components thyroid hormone biosynthesis requires, and TPO is among the genes most frequently carrying biallelic variants in congenital hypothyroidism screening cohorts.
Show evidence (1 reference)
PMID:29650690 SUPPORT Human Clinical
"Our results showed that 57 patients (51.82%) carried biallelic mutations (containing compound heterozygous mutations and homozygous mutations) in six genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone synthesis."
Documents biallelic TPO variants among the commonest genetic findings in a comprehensive screening cohort.
Thyroid dyshormonogenesis 3 (TG) MONDO:0010135
TG hgnc:11764 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in TG (hgnc:11764). hgnc:11764 is a gene from the HUGO Gene Nomenclature Committee.
Dyshormonogenetic congenital hypothyroidism caused by biallelic thyroglobulin variants. Thyroglobulin is the iodine acceptor protein that thyroid hormone biosynthesis requires.
Show evidence (1 reference)
PMID:28648508 SUPPORT REVIEW SYNTHESIS Human Clinical
"TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes."
Names TG among the genes in which mutations cause thyroid dyshormonogenesis.
Thyroid dyshormonogenesis 4 (IYD, iodotyrosine deiodinase deficiency) MONDO:0010136
IYD hgnc:21071 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in IYD (hgnc:21071). hgnc:21071 is a gene from the HUGO Gene Nomenclature Committee.
Dyshormonogenetic congenital hypothyroidism caused by biallelic IYD variants. IYD, also called DEHAL1, controls the reuse of iodide for thyroid hormone synthesis, so the defect removes iodide recycling rather than a step of hormone assembly. Reported patients had severe goitrous hypothyroidism presenting in infancy or childhood, and thyroid function can be normal at birth, so cases may be missed by newborn screening.
Show evidence (3 references)
PMID:18434651 SUPPORT Human Clinical
"Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase."
Establishes biallelic IYD variants with reduced enzyme activity as the cause of this subtype.
PMID:18434651 SUPPORT Human Clinical
"Patients had severe goitrous hypothyroidism, which was evident in infancy and childhood."
Source for the goitrous phenotype and its age at presentation stated in this subtype description.
PMID:18434651 SUPPORT Human Clinical
"Because infants with DEHAL1 defects may have normal thyroid function at birth, they may be missed by neonatal screening programs for congenital hypothyroidism."
Source for the statement that newborn screening can miss this subtype, which is the practical reason to record it separately.
Thyroid dyshormonogenesis 5 (DUOXA2) MONDO:0010137
DUOXA2 hgnc:32698 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in DUOXA2 (hgnc:32698). hgnc:32698 is a gene from the HUGO Gene Nomenclature Committee.
Dyshormonogenetic congenital hypothyroidism caused by biallelic DUOXA2 variants. HGNC names DUOXA2 dual oxidase maturation factor 2, and the DUOX system is what supplies the hydrogen peroxide thyroid hormone biosynthesis requires, so DUOXA2 and DUOX2 defects act at the same step.
Show evidence (2 references)
PMID:29650690 SUPPORT Human Clinical
"Our results showed that 57 patients (51.82%) carried biallelic mutations (containing compound heterozygous mutations and homozygous mutations) in six genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone synthesis."
Documents biallelic DUOXA2 variants in a comprehensive screening cohort of congenital hypothyroidism.
PMID:28648508 SUPPORT BACKGROUND Other
"Biosynthesis of thyroid hormones requires the presence of iodide, thyroid peroxidase (TPO), a supply of hydrogen peroxide (DUOX system), an iodine acceptor protein, thyroglobulin (TG), and the rescue and recycling of iodide by the action of iodotyrosine deiodinase or iodotyrosine dehalogenase 1..."
Source for the statement that the DUOX system supplies the hydrogen peroxide hormone biosynthesis requires, which is the step DUOXA2 acts at together with DUOX2. The sentence states established physiology rather than a result of this review.
Thyroid dyshormonogenesis 6 (DUOX2) MONDO:0011792
DUOX2 hgnc:13273 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in DUOX2 (hgnc:13273). hgnc:13273 is a gene from the HUGO Gene Nomenclature Committee.
Dyshormonogenetic congenital hypothyroidism caused by DUOX2 variants. DUOX2 supplies the hydrogen peroxide that thyroid peroxidase requires. DUOX2 had the highest variant rate in a Chinese newborn-screening cohort, and carries biallelic variants in a separate Chinese screening series.
Show evidence (2 references)
PMID:37390946 SUPPORT Human Clinical
"DUOX2 gene had the highest variant rate, followed by TG, TPO and TSHR gene."
Source for DUOX2 being the most frequently mutated gene in this newborn screening cohort.
PMID:29650690 SUPPORT Human Clinical
"Our results showed that 57 patients (51.82%) carried biallelic mutations (containing compound heterozygous mutations and homozygous mutations) in six genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone synthesis."
Independent cohort in which DUOX2 is among the genes carrying biallelic variants.
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Pathophysiology

6
Thyroid Gland Dysgenesis
The most common cause of permanent primary congenital hypothyroidism is abnormal thyroid gland development, including thyroid agenesis, ectopy, or hypoplasia, resulting in insufficient thyroid hormone production from birth. Thyroid dysgenesis accounts for 65-85% of primary CH cases.
thyroid follicular cell CL:0002257 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves thyroid follicular cell, annotated with epithelial cell of thyroid gland (CL:0002257). CL:0002257 is a cell type from the Cell Ontology.
TSHR hgnc:12373 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TSHR (hgnc:12373). hgnc:12373 is a gene from the HUGO Gene Nomenclature Committee. PAX8 hgnc:8622 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves PAX8 (hgnc:8622). hgnc:8622 is a gene from the HUGO Gene Nomenclature Committee. NKX2-1 hgnc:11825 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves NKX2-1 (hgnc:11825). hgnc:11825 is a gene from the HUGO Gene Nomenclature Committee. FOXE1 hgnc:3806 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves FOXE1 (hgnc:3806). hgnc:3806 is a gene from the HUGO Gene Nomenclature Committee. NKX2-5 hgnc:2488 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves NKX2-5 (hgnc:2488). hgnc:2488 is a gene from the HUGO Gene Nomenclature Committee.
Thyroid gland development GO:0030878 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal Thyroid gland development (GO:0030878). GO:0030878 is a biological process from the Gene Ontology. Thyroid hormone generation GO:0006590 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased Thyroid hormone generation (GO:0006590). GO:0006590 is a biological process from the Gene Ontology.
thyroid gland UBERON:0002046 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in thyroid gland (UBERON:0002046). UBERON:0002046 is an anatomical location from the Uberon multi-species anatomy ontology.
Computational models
Minimal Hypothalamic-Pituitary-Thyroid Feedback Model KINETIC Antimony/tellurium Severe reduction of S_thy captures thyroid agenesis/hypoplasia (PAX8, NKX2-1, FOXE1, TSHR defects), yielding low free T4 and markedly elevated TSH.
Downstream
Neurodevelopmental Impairment from Thyroid Hormone Deficiency Insufficient thyroid hormone production from dysgenetic thyroid tissue leads to thyroid hormone deficiency during critical periods of brain development.
Show evidence (2 references)
PMID:41303336 SUPPORT Human Clinical
"The primary form of CH is attributable to thyroid dysgenesis (agenesis, hypoplasia, or ectopy) in 65-85% of cases, with the remaining cases being attributed to dyshormogenesis."
Directly states the proportion of primary CH attributable to thyroid dysgenesis and its subtypes.
PMID:25729683 SUPPORT Human Clinical
"In the majority of patients, CH is caused by an abnormal development of the thyroid gland (thyroid dysgenesis) that is a sporadic disorder and accounts for 85% of cases and the remaining 15% of cases are caused by dyshormonogenesis."
Confirms thyroid dysgenesis as the predominant cause of CH and provides the 85%/15% proportion.
Defective Thyroid Hormone Biosynthesis
Inborn errors of thyroid hormone synthesis due to mutations in the genes encoding the transporters and enzymes thyroid hormone biosynthesis requires, namely the two-step iodide transport route (SLC5A5, SLC26A4), the hydrogen peroxide supply (DUOX2, DUOXA2), thyroid peroxidase (TPO), and the iodine acceptor protein thyroglobulin (TG). It typically results in goitrous hypothyroidism. The iodide rescue and recycling step, where IYD acts, is modeled as a separate upstream node.
thyroid follicular cell CL:0002257 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves thyroid follicular cell, annotated with epithelial cell of thyroid gland (CL:0002257). CL:0002257 is a cell type from the Cell Ontology.
SLC5A5 hgnc:11040 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SLC5A5 (hgnc:11040). hgnc:11040 is a gene from the HUGO Gene Nomenclature Committee. SLC26A4 hgnc:8818 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SLC26A4 (hgnc:8818). hgnc:8818 is a gene from the HUGO Gene Nomenclature Committee. DUOX2 hgnc:13273 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves DUOX2 (hgnc:13273). hgnc:13273 is a gene from the HUGO Gene Nomenclature Committee. DUOXA2 hgnc:32698 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves DUOXA2 (hgnc:32698). hgnc:32698 is a gene from the HUGO Gene Nomenclature Committee. TPO hgnc:12015 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TPO (hgnc:12015). hgnc:12015 is a gene from the HUGO Gene Nomenclature Committee. TG hgnc:11764 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TG (hgnc:11764). hgnc:11764 is a gene from the HUGO Gene Nomenclature Committee.
Thyroid hormone generation GO:0006590 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased Thyroid hormone generation (GO:0006590). GO:0006590 is a biological process from the Gene Ontology.
thyroid gland UBERON:0002046 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in thyroid gland (UBERON:0002046). UBERON:0002046 is an anatomical location from the Uberon multi-species anatomy ontology.
Computational models
Minimal Hypothalamic-Pituitary-Thyroid Feedback Model KINETIC Antimony/tellurium Reduced thyroid secretory capacity S_thy captures dyshormonogenesis (TPO, TG, DUOX2, SLC5A5 defects); the compensatory TSH rise is emergent from the feedback loop.
Downstream
Neurodevelopmental Impairment from Thyroid Hormone Deficiency Impaired thyroid hormone synthesis leads to the same downstream thyroid hormone deficiency as dysgenesis, though the thyroid gland is present and often goitrous.
Goiter Dyshormonogenesis can produce goitrous congenital hypothyroidism with thyroid enlargement.
Show evidence (4 references)
PMID:29650690 SUPPORT Human Clinical
"Our results showed that 57 patients (51.82%) carried biallelic mutations (containing compound heterozygous mutations and homozygous mutations) in six genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone synthesis."
Demonstrates that dyshormonogenesis genes are the most common genetic cause identified in a comprehensive screening study.
PMID:37390946 SUPPORT Human Clinical
"DUOX2 gene had the highest variant rate, followed by TG, TPO and TSHR gene."
Confirms the relative frequency of dyshormonogenesis gene variants in a newborn screening cohort.
PMID:28648508 SUPPORT REVIEW SYNTHESIS Human Clinical
"TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes."
Names the full gene set bound on this node, and is what licenses binding SLC5A5 and SLC26A4 here alongside the organification and thyroglobulin genes.
+ 1 more reference
Impaired Hypothalamic-Pituitary TSH Drive
Deficient hypothalamic TRH signaling or pituitary thyrotroph dysfunction leads to inadequate TSH secretion, producing low free T4 with inappropriately low or normal TSH.
thyrotroph CL:0000476 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves thyrotroph (CL:0000476). CL:0000476 is a cell type from the Cell Ontology.
Thyroid-stimulating hormone secretion GO:0070460 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased Thyroid-stimulating hormone secretion (GO:0070460). GO:0070460 is a biological process from the Gene Ontology.
hypothalamus-pituitary axis UBERON:0004092 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in hypothalamus-pituitary axis (UBERON:0004092). UBERON:0004092 is an anatomical location from the Uberon multi-species anatomy ontology.
Computational models
Minimal Hypothalamic-Pituitary-Thyroid Feedback Model KINETIC Antimony/tellurium Reduced pituitary capacity P_pit reproduces central hypothyroidism: low free T4 with inappropriately normal (non-elevated) TSH, the feature that distinguishes it from primary hypothyroidism.
Downstream
Neurodevelopmental Impairment from Thyroid Hormone Deficiency Inadequate TSH drive results in insufficient thyroid hormone production, causing the same downstream neurodevelopmental risk.
Prolonged Neonatal Jaundice Central congenital hypothyroidism can present with prolonged neonatal jaundice.
Hypotonia Severe central congenital hypothyroidism can manifest with neonatal hypotonia.
Macroglossia Severe central congenital hypothyroidism can cause macroglossia.
Umbilical Hernia Severe central congenital hypothyroidism can manifest with umbilical hernia.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"If the serum fT4 is low, and TSH is low, normal or slightly elevated, the diagnosis central CH should be considered"
The consensus guidelines describe the biochemical pattern of central CH reflecting inadequate TSH drive.
Transient Thyroid Dysfunction
Transient congenital hypothyroidism results from reversible disruption of thyroid function, most commonly due to transplacental passage of maternal TSH receptor-blocking antibodies, exposure to excess iodine, or hypothalamic-pituitary-thyroid axis immaturity in premature infants.
Thyroid hormone generation GO:0006590 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased Thyroid hormone generation (GO:0006590). GO:0006590 is a biological process from the Gene Ontology.
Downstream
Neurodevelopmental Impairment from Thyroid Hormone Deficiency Even transient thyroid hormone deficiency during critical neonatal brain development may cause neurodevelopmental harm if untreated.
Show evidence (2 references)
PMID:20537182 SUPPORT Human Clinical
"Transient CH most commonly occurs in preterm infants born in areas of endemic iodine deficiency."
Identifies prematurity and iodine deficiency as common causes of transient CH.
PMID:33272083 SUPPORT Human Clinical
"the prevalence of transient CH has steadily increased. In a number of studies, factors have been identified that increase the likelihood of transient disease, such as sex (more often in boys)"
Guidelines document the increasing prevalence and risk factors for transient CH.
Neurodevelopmental Impairment from Thyroid Hormone Deficiency
Thyroid hormone is indispensable for brain development during fetal life and the first 2-3 years. Deficiency during this critical period causes irreversible neurodevelopmental damage if untreated, historically known as cretinism.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
Brain development GO:0007420 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal Brain development (GO:0007420). GO:0007420 is a biological process from the Gene Ontology.
brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in brain (UBERON:0000955). UBERON:0000955 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Intellectual Disability Untreated thyroid hormone deficiency during early brain development can cause intellectual disability.
Show evidence (2 references)
PMID:29405999 SUPPORT Human Clinical
"Congenital hypothyroidism is common and can cause severe neurodevelopmental morbidity."
Directly states the neurodevelopmental consequence of congenital hypothyroidism.
PMID:25729683 SUPPORT Human Clinical
"delayed diagnosis leads to the most severe outcome of CH, mental retardation, emphasizing the importance of neonatal screening."
Confirms that delayed diagnosis leads to irreversible intellectual disability.
Iodide Salvage Failure
Loss of iodotyrosine deiodinase activity removes the control of iodide reuse for thyroid hormone synthesis, so the follicular cell loses its intrathyroidal iodide recycling. This is the step at which IYD acts, and it is separate from iodide transport and from hormone assembly, which is why it is modeled as its own node.
thyroid follicular cell CL:0002257 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves thyroid follicular cell, annotated with epithelial cell of thyroid gland (CL:0002257). CL:0002257 is a cell type from the Cell Ontology.
IYD hgnc:21071 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves IYD (hgnc:21071). hgnc:21071 is a gene from the HUGO Gene Nomenclature Committee.
iodotyrosine deiodinase activity GO:0140616 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased iodotyrosine deiodinase activity (GO:0140616). GO:0140616 is a molecular function from the Gene Ontology.
thyroid gland UBERON:0002046 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in thyroid gland (UBERON:0002046). UBERON:0002046 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Defective Thyroid Hormone Biosynthesis Without iodide salvage the follicular cell cannot sustain hormone synthesis, so the defect converges on the same reduced thyroid hormone output as the organification and transport defects.
Show evidence (2 references)
PMID:18434651 SUPPORT Human Clinical
"Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase."
Directly measures the reduced iodotyrosine deiodinase activity this node asserts, in patients with biallelic IYD variants.
PMID:18434651 SUPPORT BACKGROUND Other
"DEHAL1 has been identified as the gene encoding iodotyrosine deiodinase in the thyroid, where it controls the reuse of iodide for thyroid hormone synthesis."
States that the enzyme controls iodide reuse in the thyroid, which is the function this node describes as lost.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Congenital Hypothyroidism Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

13
Digestive 4
Prolonged Neonatal Jaundice HP:0006579 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Prolonged neonatal jaundice (HP:0006579). HP:0006579 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:33272083 SUPPORT Human Clinical
"Isolated central CH due to biallelic TSHβ gene mutations is associated with severe hypothyroidism and characterized by the typical manifestations of CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.)."
The consensus guidelines list jaundice as a typical manifestation of congenital hypothyroidism.
PMID:33272083 SUPPORT Human Clinical
"we recommend endocrine testing in all neonates with a familial history of central CH, or signs or symptoms of congenital hypopituitarism, for example, micropenis with undescended testes, hypoglycemia, prolonged jaundice, or unexplained failure to thrive."
Guidelines specifically mention prolonged jaundice as a clinical sign warranting endocrine testing for congenital hypothyroidism.
Feeding Difficulties HP:0011968 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20537182 SUPPORT Human Clinical
"Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice."
Lists feeding difficulty as a common symptom of congenital hypothyroidism.
Umbilical Hernia HP:0001537 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Umbilical hernia (HP:0001537). HP:0001537 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"Isolated central CH due to biallelic TSHβ gene mutations is associated with severe hypothyroidism and characterized by the typical manifestations of CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.)."
The consensus guidelines explicitly list umbilical hernia as a typical manifestation of congenital hypothyroidism.
Constipation HP:0002019 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Constipation (HP:0002019). HP:0002019 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20537182 SUPPORT Human Clinical
"Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice."
Lists constipation as a common symptom of congenital hypothyroidism.
Endocrine 2
Congenital Hypothyroidism HP:0000851 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Congenital hypothyroidism (HP:0000851). HP:0000851 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"The incidence of CH partly depends on the screening strategy; based on data from a number of screening programs, the incidence of primary CH lies between 1 in 3000 and 1 in 2000; the highest reported incidence of central CH is ∼1 in 16,000"
Provides the incidence of primary and central congenital hypothyroidism from the consensus guidelines.
Goiter HP:0000853 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Goiter (HP:0000853). HP:0000853 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:37390946 SUPPORT Human Clinical
"The "DUOX2 biallelic variants" group was associated with "Goiter""
Demonstrates the association of goiter with dyshormonogenesis gene variants, specifically DUOX2 biallelic mutations.
PMID:33272083 SUPPORT Human Clinical
"Children and adolescents with primary CH due to dyshomonogenesis may develop goiter and nodules; in these cases, serum TSH should be carefully targeted in the lower part of normal range and periodical ultrasound investigation is recommended to monitor thyroid volume"
Confirms goiter and nodule development in dyshormonogenesis and recommends monitoring.
Head and Neck 2
Macroglossia HP:0000158 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Macroglossia (HP:0000158). HP:0000158 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"Isolated central CH due to biallelic TSHβ gene mutations is associated with severe hypothyroidism and characterized by the typical manifestations of CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.)."
The consensus guidelines explicitly list macroglossia as a typical manifestation of congenital hypothyroidism.
Large Fontanelles HP:0000239 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Large fontanelles (HP:0000239). HP:0000239 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20537182 SUPPORT Human Clinical
"On examination, common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia."
Lists large fontanels as a common examination finding in congenital hypothyroidism.
Integument 1
Dry Skin HP:0000958 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dry skin (HP:0000958). HP:0000958 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20537182 SUPPORT Human Clinical
"On examination, common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia."
Myxedematous facies in CH includes dry, thickened skin characteristic of hypothyroidism.
Musculoskeletal 1
Hypotonia HP:0001252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypotonia (HP:0001252). HP:0001252 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"Isolated central CH due to biallelic TSHβ gene mutations is associated with severe hypothyroidism and characterized by the typical manifestations of CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.)."
The consensus guidelines explicitly list hypotonia as a typical manifestation of congenital hypothyroidism.
Nervous System 1
Intellectual Disability HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:25729683 SUPPORT Human Clinical
"Congenital hypothyroidism (CH) is the one of the most common preventable cause of mental retardation."
Directly identifies intellectual disability as the most severe preventable outcome of untreated congenital hypothyroidism.
Growth 2
Short Stature HP:0004322 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Short stature (HP:0004322). HP:0004322 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"Adequately treated children with nonsyndromic CH have normal growth and puberty, and their fertility does not differ from individuals who do not have CH"
Indirectly supports short stature as a phenotype by stating that adequately treated CH results in normal growth, implying untreated CH leads to growth failure.
Failure to Thrive HP:0001508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Failure to thrive (HP:0001508). HP:0001508 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"we recommend endocrine testing in all neonates with a familial history of central CH, or signs or symptoms of congenital hypopituitarism, for example, micropenis with undescended testes, hypoglycemia, prolonged jaundice, or unexplained failure to thrive."
The guidelines identify failure to thrive as a clinical sign prompting evaluation for congenital hypothyroidism.
🧬

Genetic Associations

12
PAX8
Gene: PAX8 hgnc:8622 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is PAX8 (hgnc:8622). hgnc:8622 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (2 references)
PMID:41303336 SUPPORT Human Clinical
"Mutations in ten genes involved in thyroid gland development during embryogenesis, TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have been identified in cohorts of patients with thyroid dysgenesis."
Lists PAX8 among the established thyroid dysgenesis genes.
PMID:29650690 SUPPORT Human Clinical
"eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead to thyroid dysgenesis were identified in eight probands."
Identifies PAX8 mutations in probands with thyroid dysgenesis in a Chinese cohort.
TSHR
Gene: TSHR hgnc:12373 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is TSHR (hgnc:12373). hgnc:12373 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (1 reference)
PMID:41303336 SUPPORT Human Clinical
"Mutations in ten genes involved in thyroid gland development during embryogenesis, TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have been identified in cohorts of patients with thyroid dysgenesis."
Lists TSHR among established thyroid dysgenesis genes.
NKX2-1
Gene: NKX2-1 hgnc:11825 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is NKX2-1 (hgnc:11825). hgnc:11825 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (1 reference)
PMID:41303336 SUPPORT Human Clinical
"Mutations in ten genes involved in thyroid gland development during embryogenesis, TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have been identified in cohorts of patients with thyroid dysgenesis."
Lists NKX2-1 among established thyroid dysgenesis genes.
FOXE1
Gene: FOXE1 hgnc:3806 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is FOXE1 (hgnc:3806). hgnc:3806 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (1 reference)
PMID:29650690 SUPPORT Human Clinical
"eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead to thyroid dysgenesis were identified in eight probands."
Identifies FOXE1 among genes with mutations leading to thyroid dysgenesis.
TPO
Gene: TPO hgnc:12015 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is TPO (hgnc:12015). hgnc:12015 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Autosomal recessive
Show evidence (1 reference)
PMID:37390946 SUPPORT Human Clinical
"the TSH levels and initial L-T4 dose were significantly higher in "TPO biallelic variants" group than those in "DUOX2 and TSHR biallelic variants" groups."
Demonstrates TPO biallelic variants cause more severe biochemical hypothyroidism than DUOX2 or TSHR variants.
DUOX2
Gene: DUOX2 hgnc:13273 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is DUOX2 (hgnc:13273). hgnc:13273 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Autosomal recessive
Show evidence (1 reference)
PMID:29650690 SUPPORT Human Clinical
"This study identified previously reported causative genes for 57/110 Chinese patients and revealed DUOX2 was the most frequently mutated gene in these patients."
Identifies DUOX2 as the most frequently mutated CH gene in a Chinese cohort of 110 patients.
TG
Gene: TG hgnc:11764 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is TG (hgnc:11764). hgnc:11764 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Autosomal recessive
Show evidence (1 reference)
PMID:29650690 SUPPORT Human Clinical
"Our results showed that 57 patients (51.82%) carried biallelic mutations (containing compound heterozygous mutations and homozygous mutations) in six genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone synthesis."
Identifies TG among the six genes with biallelic mutations in CH patients.
SLC5A5
Gene: SLC5A5 hgnc:11040 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is SLC5A5 (hgnc:11040). hgnc:11040 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (1 reference)
PMID:29650690 SUPPORT Human Clinical
"Thyroid dyshormonogenesis, which is caused by defects in thyroid hormone biosynthesis, accounts for approximately 10–15% of primary CH and is associated with the following genes: DUOX2, DUOXA2, DUOX1, TPO, TG, SLC26A4, SLC5A5 and TSHR"
Explicitly lists SLC5A5 among the genes associated with thyroid dyshormonogenesis.
DUOXA2
Gene: DUOXA2 hgnc:32698 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is DUOXA2 (hgnc:32698). hgnc:32698 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Autosomal recessive
Show evidence (1 reference)
PMID:29650690 SUPPORT Human Clinical
"Our results showed that 57 patients (51.82%) carried biallelic mutations (containing compound heterozygous mutations and homozygous mutations) in six genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone synthesis."
Identifies DUOXA2 among the six genes with biallelic mutations in thyroid hormone synthesis in CH patients.
SLC26A4
Gene: SLC26A4 hgnc:8818 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is SLC26A4 (hgnc:8818). hgnc:8818 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"Pendred syndrome due to mutations in the SLC26A4 gene (OMIM No. 274600), with or without goiter, should be considered in case of congenital sensorineural hearing loss."
Guidelines identify SLC26A4 as a cause of syndromic CH (Pendred syndrome) with hearing loss and goiter.
NKX2-5
Gene: NKX2-5 hgnc:2488 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is NKX2-5 (hgnc:2488). hgnc:2488 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SUSCEPTIBILITY
Autosomal dominant
Show evidence (4 references)
PMID:16418214 SUPPORT Human Clinical
"NKX2-5 mutational screening in 241 patients with TD allowed the identification of three heterozygous missense changes (R25C, A119S, and R161P) in four patients with TD."
The primary human genetic observation behind the NKX2-5 assignment, and the source of the counts in these notes.
PMID:16418214 SUPPORT Human Clinical
"Our results suggest a previously unknown role of NKX2-5 in the pathogenesis of TD."
The authors' own hedged conclusion, quoted so this record does not read as an established gene-disease relationship.
PMID:30304112 REFUTE Human Clinical
"No mutations were detected in any of the candidate genes."
A negative NKX2-5 screen in 63 children with thyroid dysgenesis, which is the reason this record is typed SUSCEPTIBILITY. It does not exclude NKX2-5 in individual families.
+ 1 more reference
IYD
Gene: IYD hgnc:21071 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is IYD (hgnc:21071). hgnc:21071 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Autosomal recessive
Show evidence (3 references)
PMID:18434651 SUPPORT Human Clinical
"Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase."
Establishes biallelic IYD variants with reduced enzyme activity in four patients from three families.
PMID:18434651 SUPPORT BACKGROUND Other
"DEHAL1 has been identified as the gene encoding iodotyrosine deiodinase in the thyroid, where it controls the reuse of iodide for thyroid hormone synthesis."
States the iodide-reuse function of the gene product. The sentence reports a previously established gene assignment rather than a result of this study.
PMID:28648508 SUPPORT REVIEW SYNTHESIS Human Clinical
"TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes."
Names IYD among the genes in which mutations cause thyroid dyshormonogenesis.
💊

Medical Actions

3
Levothyroxine Replacement
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: levothyroxine CHEBI:6446 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses levothyroxine, annotated with levothyroxine sodium anhydrous (CHEBI:6446). CHEBI:6446 is a therapeutic agent from Chemical Entities of Biological Interest.
Levothyroxine is the standard treatment for congenital hypothyroidism. Early initiation within 2 weeks of birth at doses of 10-15 mcg/kg/day is critical to prevent irreversible neurodevelopmental damage.
Mechanism Target:
MODULATES Neurodevelopmental Impairment from Thyroid Hormone Deficiency — Exogenous levothyroxine bypasses the endogenous thyroid hormone deficiency, preventing neurodevelopmental impairment when started early.
Show evidence (1 reference)
PMID:29405999 SUPPORT Human Clinical
"Early and adequate treatment with levothyroxine results in excellent neurodevelopmental outcomes for most patients with congenital hypothyroidism."
Directly supports the efficacy of early levothyroxine treatment in preventing neurodevelopmental morbidity.
Target Phenotypes: Congenital hypothyroidism HP:0000851 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Congenital hypothyroidism (HP:0000851). HP:0000851 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:33272083 SUPPORT Human Clinical
"LT4 treatment should be started as soon as possible, not later than 2 weeks after birth or immediately after confirmatory (serum) thyroid function testing"
Consensus guideline recommendation for early levothyroxine treatment.
PMID:25729683 SUPPORT Human Clinical
"Treatment should be started promptly and infant should be rendered euthyroid as early as possible, as there is an inverse relationship between intelligence quotient (IQ) and the age at diagnosis."
Demonstrates the critical importance of early treatment with the inverse IQ-diagnosis age relationship.
Newborn Screening
Action: disease screeningNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is disease screening (NCIT:C15419). NCIT:C15419 is a clinical intervention from the NCI Thesaurus. Ontology label: Disease Screening NCIT:C15419
Universal newborn screening programs detect congenital hypothyroidism through TSH and/or T4 measurement from heel-prick dried blood spots, enabling early treatment before clinical symptoms develop.
Target Phenotypes: Congenital hypothyroidism HP:0000851 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Congenital hypothyroidism (HP:0000851). HP:0000851 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:33272083 SUPPORT Human Clinical
"Early detection and treatment of CH through neonatal screening prevent irreversible neurodevelopmental delay and optimize its developmental outcome"
Strong recommendation for universal newborn screening from the consensus guidelines.
PMID:33272083 SUPPORT Human Clinical
"Neonatal screening for CH has almost eliminated the profound negative effects of TH deficiency on growth and neurodevelopment (cretinism) in those countries where it has been established."
Documents the public health success of newborn screening in preventing cretinism.
Genetic Counseling
Action: Genetic CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic Counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. NCIT:C15240
Targeted genetic counseling for families with congenital hypothyroidism, particularly for dyshormonogenesis (25% recurrence risk for autosomal recessive forms) and familial thyroid dysgenesis.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"Counseling should include explaining inheritance and the risk of recurrence of the patient's primary or central form of CH, based on the CH subtype, the family history, and, if known, the (genetic) cause"
Guideline recommendation for targeted genetic counseling in CH families.
🔬

Biochemical Markers

2
Elevated TSH (Elevated)
Context: Newborn screening and diagnostic evaluation
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"the most sensitive test for detecting primary CH is measurement of thyrotropin (TSH)"
Confirms elevated TSH as the primary screening and diagnostic marker for primary congenital hypothyroidism.
Low Free Thyroxine (Decreased)
Context: Diagnostic evaluation
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"If the serum fT4 concentration is below and TSH clearly above the age-specific reference interval, then levothyroxine (LT4) treatment should be started immediately"
Confirms low fT4 as a key diagnostic finding triggering treatment.
🔬

Diagnosis

4
Newborn screening (TSH-based)
Universal newborn screening using TSH measurement from dried blood spots collected 48 hours after birth is the primary method of detecting primary congenital hypothyroidism.
disease screening NCIT:C15419 NCI Thesaurus (NCIT)
TSH, DBS LOINC:29575-8 Logical Observation Identifiers Names and Codes (LOINC)
Reference Ranges
Thyrotropin [Units/volume] in DBS (newborn screening, Republic of Ireland national programme (whole-blood TSH, since 1979))
Screen negative (< 8 m[IU]/L) Screen positive (≥ 8 m[IU]/L)
Screen positive: Whole-blood TSH at or above the programme cut-off is a presumptive positive screen for primary congenital hypothyroidism and leads to confirmatory serum TSH and free T4.
Source wording: "The NBS programme in the Republic of Ireland has used a cut-off of 8 mU/L since 1979." Whole-blood (dried-blood-spot) TSH in mU/L; the source itself notes there is no consensus on the optimal screening cut-off, so this band records Ireland's threshold rather than a universal one.
Show evidence (1 reference)
PMID:29804122 SUPPORT Human Clinical
"The NBS programme in the Republic of Ireland has used a cut-off of 8 mU/L since 1979."
States the whole-blood TSH screening cut-off used by the Irish national programme.
Thyrotropin [Units/volume] in DBS (newborn screening, Republic of Macedonia national programme (DELFIA fluoroimmunoassay, dried blood spot))
Screen negative (< 10 m[IU]/L) Screen positive (≥ 10 m[IU]/L)
Screen positive: Dried-blood-spot TSH at or above the programme cut-off led to recall for confirmatory testing.
Source wording: "The TSH cutoff level was 10 mU/L blood." Recorded as a second programme's cut-off; 10 mU/L is also the level several other programmes in the searched literature report, but each is cited only where its own paper states it.
Show evidence (1 reference)
PMID:25192932 SUPPORT Human Clinical
"The TSH cutoff level was 10 mU/L blood."
States the dried-blood-spot TSH cut-off of the Macedonian national programme.
LOINC codes and labels were read from the Monarch KG and seeded into cache/loinc/terms.csv by scripts/seed_loinc_cache.sh. LOINC's only quantitative DBS thyrotropin code is Thyrotropin [Units/volume] in DBS (LOINC:29575-8), which matches the mU/L of both cited programmes; the unit is written in UCUM as m[IU]/L. This row is the TSH-primary strategy; programmes that screen T4-first use a different analyte (Thyroxine (T4) [Mass/volume] in DBS, LOINC:31144-9) and are not bound here because the entry's screening row and cited sources are TSH-based.
Show evidence (2 references)
PMID:33272083 SUPPORT Human Clinical
"Early detection and treatment of CH through neonatal screening prevent irreversible neurodevelopmental delay and optimize its developmental outcome"
Strong recommendation for universal newborn screening from consensus guidelines.
PMID:25192932 SUPPORT Human Clinical
"we measured thyroid-stimulating hormone (TSH) levels in dried blood spot specimens using the DELFIA fluoroimmunoassay, over a period of 12 years."
A national programme measuring dried-blood-spot TSH as the screening measurement for congenital hypothyroidism.
Confirmatory serum thyroid function testing
Confirmatory measurement of serum fT4 and TSH is required after an abnormal screening result. If serum TSH is >20 mU/L, treatment should start even if fT4 is normal.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"If the serum fT4 concentration is below and TSH clearly above the age-specific reference interval, then levothyroxine (LT4) treatment should be started immediately"
Guidelines specify the confirmatory testing criteria for initiating treatment.
Thyroid imaging
Thyroid scintigraphy and/or ultrasonography to determine thyroid morphology (dysgenesis vs gland in situ), which informs the etiology and prognosis.
nuclear medicine imaging procedure NCIT:C62667 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"We recommend imaging of the thyroid gland using either radioisotope scanning (scintigraphy) with or without the perchlorate discharge test, or ultrasonography (US), or both"
Guidelines recommend thyroid imaging to determine the etiology of CH.
Genetic testing
Molecular genetic testing to identify causative mutations, particularly for dyshormonogenesis genes and thyroid dysgenesis transcription factors, informing genetic counseling.
genetic testing NCIT:C15709 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"If genetic testing is performed, its aim should be improving diagnosis, treatment, or prognosis"
Guidelines support genetic testing when it informs clinical management.
📊

Prevalence

2
Worldwide (primary CH)
Birth Prevalence 40.0 per 100,000 1–9 per 10,000 (births)
Incidence of primary CH is 1 in 2000 to 1 in 3000 newborns depending on screening strategy.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"the incidence of primary CH lies between 1 in 3000 and 1 in 2000; the highest reported incidence of central CH is ∼1 in 16,000"
Consensus guidelines provide incidence ranges for primary and central CH from multiple screening programs.
Worldwide (central CH)
Birth Prevalence 6.0 per 100,000 1–9 per 100,000 (births)
Incidence of central CH is approximately 1 in 16,000 newborns.
Show evidence (1 reference)
PMID:33272083 SUPPORT Human Clinical
"the incidence of primary CH lies between 1 in 3000 and 1 in 2000; the highest reported incidence of central CH is ∼1 in 16,000"
Central CH has a lower incidence than primary CH.
📊

Related Datasets

2
Epigenome wide Association and Stochastic Epigenetic Mutation analysis on 23 twin pairs heterogeneously affected by Congenital Hypothyroidism (CH). geo:GSE161041
We performed a whole-genome DNA methylation analysis (Infinium HumanMethylation450 BeadChip) on peripheral whole blood of 23 twin pairs (10 monozygotic and 13 dizygotic) heterogeneously (4 concordant and 19 discordant) affected by Congenital Hypothyroidism (CH) at birth.
human METHYLATION n=46
PMID:36071330
Identified by GEO DataSets index search for Congenital Hypothyroidism (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
Screening for chromosomal aberrations by array CGH in 74 patients with congenital hypothyroidism geo:GSE18152
Congenital Hypothyroidism occurs in 1:3500 live births and is therefore the most common congenital endocrine disorder. A spectrum of defective thyroid morphology, termed thyroid dysgenesis, represents 80% of permanent CH cases. Although several candidate genes have been implicated in thyroid development, comprehensive screens failed to detect mutation carriers in a significant number of patients with non-syndromic TD. Due to the sporadic occurrence of TD, de novo chromosomal rearrangements are conceivably representing one of the molecular mechanisms participating in its aetiology.
human n=80
PMID:20427504
Identified by GEO DataSets index search for Congenital Hypothyroidism (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
🧮

Computational Models

1
Minimal Hypothalamic-Pituitary-Thyroid Feedback Model SBML Antimony/tellurium KINETIC
A minimal two-state (TSH, free T4) ODE model of the hypothalamic-pituitary-thyroid negative-feedback loop, authored for dismech-perturb (analogous to the hand-authored CKD-MBD Antimony component; not a BioModels deposit). Pituitary TSH output is suppressed by free T4; the thyroid secretes T4 in proportion to TSH scaled by secretory capacity S_thy. Calibrated to a euthyroid steady state (TSH ~1.5 mU/L, free T4 ~15 pmol/L). Reducing S_thy reproduces primary congenital hypothyroidism (dysgenesis / dyshormonogenesis) with the compensatory TSH rise; reducing pituitary capacity reproduces central hypothyroidism (low free T4 with inappropriately normal TSH); and the exogenous levothyroxine term (LT4) restores euthyroidism, with over-replacement driving iatrogenic thyrotoxicosis.
Model page: rules, runs →
Variable Model ID Unit Ontology Mappings Phenotype Thresholds
TSH
Plasma thyroid-stimulating hormone at steady state; rises as thyroid secretory capacity falls (primary hypothyroidism) and is suppressed by levothyroxine over-replacement.
 TSH mU/L
Elevated circulating thyroid-stimulating hormone concentration above 4.0
mild 4.0 moderate 10.0 severe 20.0
FT4
Free thyroxine at steady state; falls in primary and central hypothyroidism and rises above normal with levothyroxine over-replacement.
 FT4 pmol/L
Hypothyroidism below 0.85× baseline
mild 0.85× baseline moderate 0.7× baseline severe 0.55× baseline
Hyperthyroidism above 20.0
mild 20.0 moderate 24.0 severe 30.0
Simulation results — 15 scenarios run with dismech-perturb (tellurium / libRoadRunner CVODE) over 2000 h; baseline S_thy = 1.0
Scenario FT4 (pmol/L) TSH (mU/L) Activated phenotypes
Healthy baseline
S_thy = 1.0
 15.023105 1.482311 reference
Subclinical primary hypothyroidism (S_thy=0.3)
drives Defective Thyroid Hormone Biosynthesis
12.244755
0.82× baseline
 4.014918
2.71× baseline
 Elevated circulating thyroid-stimulating hormone concentration · mild Hypothyroidism · mild
Overt primary hypothyroidism (S_thy=0.1)
drives Defective Thyroid Hormone Biosynthesis
10.095095
0.67× baseline
 9.895095
6.68× baseline
 Elevated circulating thyroid-stimulating hormone concentration · mild Hypothyroidism · moderate
Athyreosis / severe hypothyroidism (S_thy=0.03)
drives Thyroid Gland Dysgenesis
8.000092
0.53× baseline
 26.000307
17.54× baseline
 Elevated circulating thyroid-stimulating hormone concentration · severe Hypothyroidism · severe
Central (pituitary) hypothyroidism (P_pit low)
drives Impaired Hypothalamic-Pituitary TSH Drive
10.853411
0.72× baseline
 1.065341
0.72× baseline
 Hypothyroidism · mild
TPO loss-of-function (dyshormonogenesis)
drives Defective Thyroid Hormone Biosynthesis
10.095095
0.67× baseline
 9.895095
6.68× baseline
 Elevated circulating thyroid-stimulating hormone concentration · mild Hypothyroidism · moderate
TG loss-of-function (dyshormonogenesis)
drives Defective Thyroid Hormone Biosynthesis
10.095095
0.67× baseline
 9.895095
6.68× baseline
 Elevated circulating thyroid-stimulating hormone concentration · mild Hypothyroidism · moderate
DUOX2 loss-of-function (dyshormonogenesis)
drives Defective Thyroid Hormone Biosynthesis
10.853411
0.72× baseline
 7.102274
4.79× baseline
 Elevated circulating thyroid-stimulating hormone concentration · mild Hypothyroidism · mild
SLC5A5/NIS loss-of-function (iodide transport defect)
drives Defective Thyroid Hormone Biosynthesis
10.095095
0.67× baseline
 9.895095
6.68× baseline
 Elevated circulating thyroid-stimulating hormone concentration · mild Hypothyroidism · moderate
TSHR loss-of-function (TSH resistance)
drives Thyroid Gland Dysgenesis
10.853411
0.72× baseline
 7.102274
4.79× baseline
 Elevated circulating thyroid-stimulating hormone concentration · mild Hypothyroidism · mild
PAX8 loss-of-function (thyroid dysgenesis)
drives Thyroid Gland Dysgenesis
8.869514
0.59× baseline
 17.339029
11.70× baseline
 Elevated circulating thyroid-stimulating hormone concentration · moderate Hypothyroidism · moderate
NKX2-1 loss-of-function (thyroid dysgenesis)
drives Thyroid Gland Dysgenesis
8.869514
0.59× baseline
 17.339029
11.70× baseline
 Elevated circulating thyroid-stimulating hormone concentration · moderate Hypothyroidism · moderate
FOXE1 loss-of-function (thyroid agenesis)
drives Thyroid Gland Dysgenesis
8.869514
0.59× baseline
 17.339029
11.70× baseline
 Elevated circulating thyroid-stimulating hormone concentration · moderate Hypothyroidism · moderate
Levothyroxine, under-dosed (residual hypothyroidism)
drives Defective Thyroid Hormone Biosynthesis
11.57508
0.77× baseline
 5.250267
3.54× baseline
 Elevated circulating thyroid-stimulating hormone concentration · mild Hypothyroidism · mild
Levothyroxine, full replacement (euthyroid restored)
drives Defective Thyroid Hormone Biosynthesis
14.524937
0.97× baseline
 1.749789
1.18× baseline
 none
Levothyroxine, over-replacement (iatrogenic thyrotoxicosis)
drives Defective Thyroid Hormone Biosynthesis
24.042932
1.60× baseline
 0.143108
0.10× baseline
 Hyperthyroidism · moderate
Derived artifact, regenerated by just gen-model-results — not curated evidence. Values rounded to 6 decimals. Config 9d52d1d81903, model.xml 0b426f0a5a26. Phenotypes activate per the curated variable thresholds.
Pathograph links
Defective Thyroid Hormone Biosynthesis Reduced thyroid secretory capacity S_thy captures dyshormonogenesis (TPO, TG, DUOX2, SLC5A5 defects); the compensatory TSH rise is emergent from the feedback loop.
Thyroid Gland Dysgenesis Severe reduction of S_thy captures thyroid agenesis/hypoplasia (PAX8, NKX2-1, FOXE1, TSHR defects), yielding low free T4 and markedly elevated TSH.
Impaired Hypothalamic-Pituitary TSH Drive Reduced pituitary capacity P_pit reproduces central hypothyroidism: low free T4 with inappropriately normal (non-elevated) TSH, the feature that distinguishes it from primary hypothyroidism.
Findings
Central hypothyroidism is modeled by reducing pituitary TSH secretion, producing low thyroid hormone with non-elevated TSH - the P_pit perturbation in this model.
Show evidence (1 reference)
PMID:18844475 SUPPORT Computational
"We simulated steady-state plasma T(3), T(4), and TSH concentrations in response to varying degrees of central hypothyroidism, reducing TSH secretion from 50% down to 0.1% of normal"
Confirms that reducing pituitary TSH secretion is the accepted way to simulate central hypothyroidism, matching this model's P_pit perturbation.
Levothyroxine replacement normalizes the thyroid axis in the simulator, the basis for the model's levothyroxine (LT4) treatment scenarios.
Show evidence (1 reference)
PMID:18844475 SUPPORT Computational
"We then explored three contemporary clinical issues with the new model: combined triiodothyronine (T(3))/thyroxine (T(4)) versus T(4)-only treatment, parenteral levothyroxine (L-T(4)) administration, and central hypothyroidism"
Shows the simulator is used to study levothyroxine (L-T4) replacement, the treatment reproduced by this model's LT4 scenarios.
Notes
Wired for dismech-perturb (models/hpt_feedback_axis/config.yaml; Antimony source models/hpt_feedback_axis/model.ant). The disease-severity dial is thyroid secretory capacity S_thy (baseline_gfr 1.0 = normal). Levothyroxine is an exogenous, TSH-independent T4 source (LT4); treatment scenarios titrate it from under-replacement (residual high TSH) through full replacement (euthyroid) to over-replacement (suppressed TSH, elevated free T4 = iatrogenic thyrotoxicosis). Thresholds are calibrated to model steady-state values, not clinical assay reference ranges.
Show evidence (1 reference)
PMID:18844475 SUPPORT Computational
"feedback control system (FBCS) simulation model of human thyroid hormone (TH) regulation to include explicit representation of hypothalamic and pituitary dynamics"
Establishes the validated feedback-control-simulator approach to the HPT axis that this minimal two-state model encodes in reduced form.
{ }

Source YAML

click to show 
name: Congenital Hypothyroidism
creation_date: '2026-05-14T20:54:37Z'
category: Complex
disease_term:
  preferred_term: congenital hypothyroidism
  term:
    id: MONDO:0018612
    label: congenital hypothyroidism
parents:
- hypothyroidism
description: Congenital hypothyroidism is thyroid hormone deficiency present at birth
  and is one of the most common preventable causes of intellectual disability worldwide.
  The primary form, caused by thyroid dysgenesis or dyshormonogenesis, accounts for
  the vast majority of cases with an incidence of 1 in 2000 to 1 in 3000. Universal
  newborn screening enables early detection and treatment with levothyroxine, which
  prevents irreversible neurodevelopmental damage when initiated within the first
  two weeks of life.
has_subtypes:
- name: Permanent Primary
  display_name: Permanent Primary Congenital Hypothyroidism
  children:
  - TSHR Resistance
  - CHNG2
  - CHNG5
  - Dyshormonogenesis
  description: Permanent thyroid hormone deficiency due to thyroid gland dysgenesis
    (agenesis, ectopy, hypoplasia) or dyshormonogenesis, requiring lifelong levothyroxine
    replacement. Thyroid dysgenesis accounts for 65-85% of primary CH cases.
  subtype_term:
    preferred_term: permanent congenital hypothyroidism
    term:
      id: MONDO:0016408
      label: permanent congenital hypothyroidism
- name: Transient
  display_name: Transient Congenital Hypothyroidism
  description: Temporary thyroid hormone deficiency at birth that resolves spontaneously,
    commonly due to maternal antithyroid antibodies, iodine excess or deficiency,
    or prematurity.
  subtype_term:
    preferred_term: transient congenital hypothyroidism
    term:
      id: MONDO:0015792
      label: transient congenital hypothyroidism
- name: Central
  display_name: Central Congenital Hypothyroidism
  description: Congenital thyroid hormone deficiency caused by insufficient hypothalamic
    or pituitary stimulation of the thyroid gland, with low free T4 and non-elevated
    TSH. Incidence approximately 1 in 16,000.
  subtype_term:
    preferred_term: central congenital hypothyroidism
    term:
      id: MONDO:0016410
      label: central congenital hypothyroidism
- name: Dyshormonogenesis
  display_name: Familial Thyroid Dyshormonogenesis
  children:
  - TDH1
  - TDH2A
  - TDH3
  - TDH4
  - TDH5
  - TDH6
  description: Autosomal recessive defects in thyroid hormone synthesis enzymes and
    transporters (TPO, TG, DUOX2, DUOXA2, SLC5A5, SLC26A4) plus the iodide salvage
    enzyme IYD, causing goitrous congenital hypothyroidism.
  subtype_term:
    preferred_term: familial thyroid dyshormonogenesis
    term:
      id: MONDO:0010132
      label: familial thyroid dyshormonogenesis
- name: TSHR Resistance
  display_name: TSH resistance due to TSHR loss of function
  classification: molecular_etiology
  description: >-
    Primary congenital hypothyroidism caused by loss-of-function variants in the
    TSH receptor, which leave follicular cells hyporesponsive to TSH. MONDO
    names the subtype after the receptor rather than after a gland
    malformation.
  subtype_term:
    preferred_term: hypothyroidism due to TSH receptor mutations
    term:
      id: MONDO:0010142
      label: hypothyroidism due to TSH receptor mutations
  genes:
  - preferred_term: TSHR
    term:
      id: hgnc:12373
      label: TSHR
  evidence:
  - reference: PMID:41303336
    reference_title: 'Molecular Genetics of Primary Congenital Hypothyroidism: Established
      and Emerging Contributors to Thyroid Dysgenesis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Mutations in ten genes involved in thyroid gland development during embryogenesis,
      TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have
      been identified in cohorts of patients with thyroid dysgenesis.
    explanation: Lists TSHR among the genes in which mutations have been identified in thyroid dysgenesis cohorts.
- name: CHNG2
  display_name: Congenital nongoitrous hypothyroidism 2 (PAX8)
  classification: molecular_etiology
  description: >-
    Primary congenital hypothyroidism caused by PAX8 variants. PAX8 is one of
    the thyroid transcription factor genes in which mutations have been
    identified in cohorts of patients with thyroid dysgenesis.
  subtype_term:
    preferred_term: hypothyroidism, congenital, nongoitrous, 2
    term:
      id: MONDO:0024264
      label: hypothyroidism, congenital, nongoitrous, 2
  genes:
  - preferred_term: PAX8
    term:
      id: hgnc:8622
      label: PAX8
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead
      to thyroid dysgenesis were identified in eight probands.
    explanation: Identifies PAX8 mutations in probands with thyroid dysgenesis in a Chinese cohort.
- name: CHNG5
  display_name: Congenital nongoitrous hypothyroidism 5 (NKX2-5)
  classification: molecular_etiology
  description: >-
    MONDO assigns this term to NKX2-5, a transcription factor whose main role is
    in heart development. The evidence is contested and this subtype is recorded
    as a candidate rather than an established one: the original report found
    three heterozygous missense changes in four of 241 patients with thyroid
    dysgenesis and described the role as previously unknown, while a later
    screen of 63 Brazilian children with thyroid dysgenesis found no mutations
    in NKX2-5 or in the other candidate genes it examined.
  subtype_term:
    preferred_term: hypothyroidism, congenital, nongoitrous, 5
    term:
      id: MONDO:0009154
      label: hypothyroidism, congenital, nongoitrous, 5
  genes:
  - preferred_term: NKX2-5
    term:
      id: hgnc:2488
      label: NKX2-5
  evidence:
  - reference: PMID:16418214
    reference_title: "Missense mutation in the transcription factor NKX2-5: a novel molecular event in the pathogenesis of thyroid dysgenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "NKX2-5 mutational screening in 241 patients with TD allowed the identification of three heterozygous missense changes (R25C, A119S, and R161P) in four patients with TD."
    explanation: The primary human genetic evidence for this subtype, and the source of the yield quoted in its description.
  - reference: PMID:16418214
    reference_title: "Missense mutation in the transcription factor NKX2-5: a novel molecular event in the pathogenesis of thyroid dysgenesis."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Our results indicate that Nkx2-5(-/-) embryos exhibit thyroid bud hypoplasia, providing evidence that NKX2-5 plays a role in thyroid organogenesis and that NKX2-5 mutations contribute to TD."
    explanation: Mouse evidence that NKX2-5 acts in thyroid organogenesis, offered by the same study in support of the human finding.
  - reference: PMID:30304112
    reference_title: "Mutation screening in the genes PAX-8, NKX2-5, TSH-R, HES-1 in cohort of 63 Brazilian children with thyroid dysgenesis."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "No mutations were detected in any of the candidate genes."
    explanation: A negative screen of NKX2-5 in 63 children with thyroid dysgenesis. It does not exclude NKX2-5 as a cause in individual families, but it counts against treating it as an established contributor, which is why this subtype is recorded as a candidate.
- name: TDH1
  display_name: Thyroid dyshormonogenesis 1 (SLC5A5, iodide transport defect)
  classification: molecular_etiology
  description: >-
    Dyshormonogenetic congenital hypothyroidism caused by biallelic SLC5A5
    variants. SLC5A5 encodes the sodium/iodide symporter, the basolateral
    transporter of the two-step iodide transport route, so the defect is at the
    entry of iodide into the follicular cell.
  subtype_term:
    preferred_term: thyroid dyshormonogenesis 1
    term:
      id: MONDO:0020716
      label: thyroid dyshormonogenesis 1
  genes:
  - preferred_term: SLC5A5
    term:
      id: hgnc:11040
      label: SLC5A5
  evidence:
  - reference: PMID:28648508
    reference_title: Iodide handling disorders (NIS, TPO, TG, IYD).
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: "TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes."
    explanation: Names SLC5A5 among the genes in which mutations cause thyroid dyshormonogenesis.
  - reference: PMID:28648508
    reference_title: Iodide handling disorders (NIS, TPO, TG, IYD).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: BACKGROUND
    snippet: "The iodide transport is a two-step process involving transporters located either in the basolateral or apical membranes, sodium iodide symporter (NIS) and pendrin (PDS), respectively."
    explanation: Source for placing SLC5A5 at the basolateral uptake step, stated as established physiology rather than as a result of this review.
- name: TDH2A
  display_name: Thyroid dyshormonogenesis 2A (TPO)
  classification: molecular_etiology
  description: >-
    Dyshormonogenetic congenital hypothyroidism caused by biallelic TPO variants.
    Thyroid peroxidase is one of the components thyroid hormone biosynthesis
    requires, and TPO is among the genes most frequently carrying biallelic
    variants in congenital hypothyroidism screening cohorts.
  subtype_term:
    preferred_term: thyroid dyshormonogenesis 2A
    term:
      id: MONDO:0010133
      label: thyroid dyshormonogenesis 2A
  genes:
  - preferred_term: TPO
    term:
      id: hgnc:12015
      label: TPO
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our results showed that 57 patients (51.82%) carried biallelic mutations
      (containing compound heterozygous mutations and homozygous mutations) in six
      genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone
      synthesis.
    explanation: Documents biallelic TPO variants among the commonest genetic findings in a comprehensive screening cohort.
- name: TDH3
  display_name: Thyroid dyshormonogenesis 3 (TG)
  classification: molecular_etiology
  description: >-
    Dyshormonogenetic congenital hypothyroidism caused by biallelic
    thyroglobulin variants. Thyroglobulin is the iodine acceptor protein that
    thyroid hormone biosynthesis requires.
  subtype_term:
    preferred_term: thyroid dyshormonogenesis 3
    term:
      id: MONDO:0010135
      label: thyroid dyshormonogenesis 3
  genes:
  - preferred_term: TG
    term:
      id: hgnc:11764
      label: TG
  evidence:
  - reference: PMID:28648508
    reference_title: Iodide handling disorders (NIS, TPO, TG, IYD).
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: "TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes."
    explanation: Names TG among the genes in which mutations cause thyroid dyshormonogenesis.
- name: TDH4
  display_name: Thyroid dyshormonogenesis 4 (IYD, iodotyrosine deiodinase deficiency)
  classification: molecular_etiology
  description: >-
    Dyshormonogenetic congenital hypothyroidism caused by biallelic IYD variants.
    IYD, also called DEHAL1, controls the reuse of iodide for thyroid hormone
    synthesis, so the defect removes iodide recycling rather than a step of
    hormone assembly. Reported patients had severe goitrous hypothyroidism
    presenting in infancy or childhood, and thyroid function can be normal at
    birth, so cases may be missed by newborn screening.
  subtype_term:
    preferred_term: thyroid dyshormonogenesis 4
    term:
      id: MONDO:0010136
      label: thyroid dyshormonogenesis 4
  genes:
  - preferred_term: IYD
    term:
      id: hgnc:21071
      label: IYD
  evidence:
  - reference: PMID:18434651
    reference_title: Mutations in the iodotyrosine deiodinase gene and hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase."
    explanation: Establishes biallelic IYD variants with reduced enzyme activity as the cause of this subtype.
  - reference: PMID:18434651
    reference_title: Mutations in the iodotyrosine deiodinase gene and hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients had severe goitrous hypothyroidism, which was evident in infancy and childhood."
    explanation: Source for the goitrous phenotype and its age at presentation stated in this subtype description.
  - reference: PMID:18434651
    reference_title: Mutations in the iodotyrosine deiodinase gene and hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Because infants with DEHAL1 defects may have normal thyroid function at birth, they may be missed by neonatal screening programs for congenital hypothyroidism."
    explanation: Source for the statement that newborn screening can miss this subtype, which is the practical reason to record it separately.
- name: TDH5
  display_name: Thyroid dyshormonogenesis 5 (DUOXA2)
  classification: molecular_etiology
  description: >-
    Dyshormonogenetic congenital hypothyroidism caused by biallelic DUOXA2
    variants. HGNC names DUOXA2 dual oxidase maturation factor 2, and the DUOX
    system is what supplies the hydrogen peroxide thyroid hormone biosynthesis
    requires, so DUOXA2 and DUOX2 defects act at the same step.
  subtype_term:
    preferred_term: thyroid dyshormonogenesis 5
    term:
      id: MONDO:0010137
      label: thyroid dyshormonogenesis 5
  genes:
  - preferred_term: DUOXA2
    term:
      id: hgnc:32698
      label: DUOXA2
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our results showed that 57 patients (51.82%) carried biallelic mutations
      (containing compound heterozygous mutations and homozygous mutations) in six
      genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone
      synthesis.
    explanation: Documents biallelic DUOXA2 variants in a comprehensive screening cohort of congenital hypothyroidism.
  - reference: PMID:28648508
    reference_title: Iodide handling disorders (NIS, TPO, TG, IYD).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: BACKGROUND
    snippet: "Biosynthesis of thyroid hormones requires the presence of iodide, thyroid peroxidase (TPO), a supply of hydrogen peroxide (DUOX system), an iodine acceptor protein, thyroglobulin (TG), and the rescue and recycling of iodide by the action of iodotyrosine deiodinase or iodotyrosine dehalogenase 1 (IYD or DEHAL1)."
    explanation: Source for the statement that the DUOX system supplies the hydrogen peroxide hormone biosynthesis requires, which is the step DUOXA2 acts at together with DUOX2. The sentence states established physiology rather than a result of this review.
- name: TDH6
  display_name: Thyroid dyshormonogenesis 6 (DUOX2)
  classification: molecular_etiology
  description: >-
    Dyshormonogenetic congenital hypothyroidism caused by DUOX2 variants. DUOX2
    supplies the hydrogen peroxide that thyroid peroxidase requires. DUOX2 had
    the highest variant rate in a Chinese newborn-screening cohort, and carries
    biallelic variants in a separate Chinese screening series.
  subtype_term:
    preferred_term: thyroid dyshormonogenesis 6
    term:
      id: MONDO:0011792
      label: thyroid dyshormonogenesis 6
  genes:
  - preferred_term: DUOX2
    term:
      id: hgnc:13273
      label: DUOX2
  evidence:
  - reference: PMID:37390946
    reference_title: Clinical, biochemical characteristics and genotype-phenotype
      analysis of congenital hypothyroidism diagnosed by newborn screening in China.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: DUOX2 gene had the highest variant rate, followed by TG, TPO and TSHR
      gene.
    explanation: Source for DUOX2 being the most frequently mutated gene in this newborn screening cohort.
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our results showed that 57 patients (51.82%) carried biallelic mutations
      (containing compound heterozygous mutations and homozygous mutations) in six
      genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone
      synthesis.
    explanation: Independent cohort in which DUOX2 is among the genes carrying biallelic variants.
inheritance:
- name: Autosomal recessive inheritance
  description: Dyshormonogenesis subtypes (TPO, TG, DUOX2, DUOXA2, SLC5A5, SLC26A4,
    IYD mutations) follow autosomal recessive inheritance with 25% recurrence risk.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Autosomal recessive inheritance of CH caused by mutations in DUOX2,
      DUOXA2, TG and TPO was confirmed by analysis of 22 family pedigrees.
    explanation: Family pedigree analysis confirms autosomal recessive inheritance
      for dyshormonogenesis genes.
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Counseling should include explaining inheritance and the risk of recurrence
      of the patient's primary or central form of CH, based on the CH subtype, the
      family history, and, if known, the (genetic) cause
    explanation: Guidelines recommend counseling on inheritance including recurrence
      risk for autosomal recessive forms.
- name: Digenic (thyroid dysgenesis)
  inheritance_term:
    preferred_term: Digenic inheritance
    term:
      id: HP:0010984
      label: Digenic inheritance
  description: >-
    Thyroid dysgenesis, long treated as sporadic, has a digenic arm. In a
    prospective nationwide French cohort of 514 screened newborns, 16 of 292
    genotyped patients (5.5%) each carried a variant in a thyroid DEVELOPMENT
    gene together with a variant in the H2O2-generation complex gene DUOX2 or
    DUOXA2. The pairing is not two arbitrary thyroid genes: one lesion impairs
    gland formation and the other impairs hormone synthesis in the gland that
    does form, and the study supported the model with familial segregation and
    in vitro cell-migration assays rather than co-occurrence alone. Note the
    scale: the digenic yield (16/292, 5.5%) nearly matched the monogenic yield
    (20/292, 6.8%) in the same cohort, so within CHTD this is not a rare
    curiosity at the edge of a mostly monogenic disease. Contributing
    loci: a thyroid development gene (the panel's CHTD set) plus DUOX2 or
    DUOXA2, all of which are already recorded in the genetic section; the DUOX2
    and DUOXA2 records also appear under the recessive dyshormonogenesis block
    above, which is the point - the same locus behaves differently depending on
    what it is paired with.
  evidence:
  - reference: PMID:39787321
    reference_title: "Digenic Inheritance Mode in Congenital Hypothyroidism Due to Thyroid Dysgenesis: HYPOTYGEN Translational Cohort Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We found a digenic mode of inheritance in 16 (5.5%) patients, each
      carrying a variant in a thyroid development gene and a variant in the H2O2
      generation complex gene DUOX2/DUOXA2.
    explanation: >-
      Quantifies the digenic arm in a prospective nationwide screened cohort and
      names the two gene classes that pair.
  - reference: PMID:39787321
    reference_title: "Digenic Inheritance Mode in Congenital Hypothyroidism Due to Thyroid Dysgenesis: HYPOTYGEN Translational Cohort Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Familial segregation analysis and in vitro functional studies supported
      this model.
    explanation: >-
      Records the corroboration that raises this above an observation of two
      variants in the same exome. Tagged HUMAN_CLINICAL for the familial
      segregation, which is the arm this entry relies on; the sentence also
      refers to the study's in vitro cell-migration assays, and cannot be split
      without breaking the quote.
- name: Sporadic occurrence
  description: Thyroid dysgenesis, the most common cause of primary CH, is typically
    sporadic with unclear inheritance. Monogenic, polygenic, and multifactorial
    inheritance have all been proposed.
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead
      to thyroid dysgenesis were identified in eight probands. These mutations were
      heterozygous in all cases and hypothyroidism was not observed in parents of
      these probands.
    explanation: Heterozygous mutations in thyroid dysgenesis genes with unaffected
      parents suggest complex or sporadic rather than simple dominant inheritance.
prevalence:
- population: Worldwide (primary CH)
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_5_PER_10000
  rate_per_100000: 40.0
  percentage: 0.04
  notes: Incidence of primary CH is 1 in 2000 to 1 in 3000 newborns depending on
    screening strategy.
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: the incidence of primary CH lies between 1 in 3000 and 1 in 2000; the
      highest reported incidence of central CH is ∼1 in 16,000
    explanation: Consensus guidelines provide incidence ranges for primary and central
      CH from multiple screening programs.
- population: Worldwide (central CH)
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 6.0
  percentage: 0.006
  notes: Incidence of central CH is approximately 1 in 16,000 newborns.
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: the incidence of primary CH lies between 1 in 3000 and 1 in 2000; the
      highest reported incidence of central CH is ∼1 in 16,000
    explanation: Central CH has a lower incidence than primary CH.
pathophysiology:
- name: Thyroid Gland Dysgenesis
  description: The most common cause of permanent primary congenital hypothyroidism
    is abnormal thyroid gland development, including thyroid agenesis, ectopy, or
    hypoplasia, resulting in insufficient thyroid hormone production from birth. Thyroid
    dysgenesis accounts for 65-85% of primary CH cases.
  subtypes:
  - Permanent Primary
  genes:
  - preferred_term: TSHR
    term:
      id: hgnc:12373
      label: TSHR
  - preferred_term: PAX8
    term:
      id: hgnc:8622
      label: PAX8
  - preferred_term: NKX2-1
    term:
      id: hgnc:11825
      label: NKX2-1
  - preferred_term: FOXE1
    term:
      id: hgnc:3806
      label: FOXE1
  - preferred_term: NKX2-5
    term:
      id: hgnc:2488
      label: NKX2-5
  locations:
  - preferred_term: thyroid gland
    term:
      id: UBERON:0002046
      label: thyroid gland
  cell_types:
  - preferred_term: thyroid follicular cell
    term:
      id: CL:0002257
      label: epithelial cell of thyroid gland
  biological_processes:
  - preferred_term: Thyroid gland development
    term:
      id: GO:0030878
      label: thyroid gland development
    modifier: ABNORMAL
  - preferred_term: Thyroid hormone generation
    term:
      id: GO:0006590
      label: thyroid hormone generation
    modifier: DECREASED
  evidence:
  - reference: PMID:41303336
    reference_title: 'Molecular Genetics of Primary Congenital Hypothyroidism: Established
      and Emerging Contributors to Thyroid Dysgenesis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The primary form of CH is attributable to thyroid dysgenesis (agenesis,
      hypoplasia, or ectopy) in 65-85% of cases, with the remaining cases being attributed
      to dyshormogenesis.
    explanation: Directly states the proportion of primary CH attributable to thyroid
      dysgenesis and its subtypes.
  - reference: PMID:25729683
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In the majority of patients, CH is caused by an abnormal development
      of the thyroid gland (thyroid dysgenesis) that is a sporadic disorder and accounts
      for 85% of cases and the remaining 15% of cases are caused by dyshormonogenesis.
    explanation: Confirms thyroid dysgenesis as the predominant cause of CH and provides
      the 85%/15% proportion.
  downstream:
  - target: Neurodevelopmental Impairment from Thyroid Hormone Deficiency
    causal_link_type: DIRECT
    description: Insufficient thyroid hormone production from dysgenetic thyroid tissue
      leads to thyroid hormone deficiency during critical periods of brain development.
    evidence:
    - reference: PMID:29405999
      reference_title: Congenital Hypothyroidism.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Congenital hypothyroidism is common and can cause severe neurodevelopmental
        morbidity.
      explanation: Links thyroid hormone deficiency from any cause to neurodevelopmental
        impairment.
- name: Defective Thyroid Hormone Biosynthesis
  description: >-
    Inborn errors of thyroid hormone synthesis due to mutations in the genes
    encoding the transporters and enzymes thyroid hormone biosynthesis requires,
    namely the two-step iodide transport route (SLC5A5, SLC26A4), the hydrogen
    peroxide supply (DUOX2, DUOXA2), thyroid peroxidase (TPO), and the iodine
    acceptor protein thyroglobulin (TG). It typically results in goitrous
    hypothyroidism. The iodide rescue and recycling step, where IYD acts, is
    modeled as a separate upstream node.
  conforms_to: "hypothyroidism_thyroid_hormone_deficiency#Thyroid Hormone Insufficiency"
  subtypes:
  - Dyshormonogenesis
  genes:
  - preferred_term: SLC5A5
    term:
      id: hgnc:11040
      label: SLC5A5
  - preferred_term: SLC26A4
    term:
      id: hgnc:8818
      label: SLC26A4
  - preferred_term: DUOX2
    term:
      id: hgnc:13273
      label: DUOX2
  - preferred_term: DUOXA2
    term:
      id: hgnc:32698
      label: DUOXA2
  - preferred_term: TPO
    term:
      id: hgnc:12015
      label: TPO
  - preferred_term: TG
    term:
      id: hgnc:11764
      label: TG
  locations:
  - preferred_term: thyroid gland
    term:
      id: UBERON:0002046
      label: thyroid gland
  cell_types:
  - preferred_term: thyroid follicular cell
    term:
      id: CL:0002257
      label: epithelial cell of thyroid gland
  biological_processes:
  - preferred_term: Thyroid hormone generation
    term:
      id: GO:0006590
      label: thyroid hormone generation
    modifier: DECREASED
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our results showed that 57 patients (51.82%) carried biallelic mutations
      (containing compound heterozygous mutations and homozygous mutations) in six
      genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone
      synthesis.
    explanation: Demonstrates that dyshormonogenesis genes are the most common genetic
      cause identified in a comprehensive screening study.
  - reference: PMID:37390946
    reference_title: Clinical, biochemical characteristics and genotype-phenotype
      analysis of congenital hypothyroidism diagnosed by newborn screening in China.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: DUOX2 gene had the highest variant rate, followed by TG, TPO and TSHR
      gene.
    explanation: Confirms the relative frequency of dyshormonogenesis gene variants
      in a newborn screening cohort.
  - reference: PMID:28648508
    reference_title: Iodide handling disorders (NIS, TPO, TG, IYD).
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: "TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes."
    explanation: Names the full gene set bound on this node, and is what licenses binding SLC5A5 and SLC26A4 here alongside the organification and thyroglobulin genes.
  - reference: PMID:28648508
    reference_title: Iodide handling disorders (NIS, TPO, TG, IYD).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: BACKGROUND
    snippet: "Biosynthesis of thyroid hormones requires the presence of iodide, thyroid peroxidase (TPO), a supply of hydrogen peroxide (DUOX system), an iodine acceptor protein, thyroglobulin (TG), and the rescue and recycling of iodide by the action of iodotyrosine deiodinase or iodotyrosine dehalogenase 1 (IYD or DEHAL1)."
    explanation: Sets out the steps each bound gene acts at, which is the basis for separating the iodide-salvage step into its own upstream node while keeping the organification and matrix genes on this one. The sentence states established physiology rather than a result of this review.
  downstream:
  - target: Neurodevelopmental Impairment from Thyroid Hormone Deficiency
    causal_link_type: DIRECT
    description: Impaired thyroid hormone synthesis leads to the same downstream thyroid
      hormone deficiency as dysgenesis, though the thyroid gland is present and often
      goitrous.
    evidence:
    - reference: PMID:29405999
      reference_title: Congenital Hypothyroidism.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Congenital hypothyroidism is common and can cause severe neurodevelopmental
        morbidity.
      explanation: Links thyroid hormone deficiency from any cause to neurodevelopmental
        impairment.
  - target: Goiter
    causal_link_type: DIRECT
    description: Dyshormonogenesis can produce goitrous congenital hypothyroidism
      with thyroid enlargement.
    evidence:
    - reference: PMID:33272083
      reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Children and adolescents with primary CH due to dyshomonogenesis may
        develop goiter and nodules; in these cases, serum TSH should be carefully
        targeted in the lower part of normal range and periodical ultrasound investigation
        is recommended to monitor thyroid volume
      explanation: The consensus guidelines directly link primary congenital hypothyroidism
        due to dyshormonogenesis with goiter and nodules.
- name: Impaired Hypothalamic-Pituitary TSH Drive
  description: Deficient hypothalamic TRH signaling or pituitary thyrotroph dysfunction
    leads to inadequate TSH secretion, producing low free T4 with inappropriately
    low or normal TSH.
  subtypes:
  - Central
  locations:
  - preferred_term: hypothalamus-pituitary axis
    term:
      id: UBERON:0004092
      label: hypothalamus-pituitary axis
  cell_types:
  - preferred_term: thyrotroph
    term:
      id: CL:0000476
      label: thyrotroph
  biological_processes:
  - preferred_term: Thyroid-stimulating hormone secretion
    term:
      id: GO:0070460
      label: thyroid-stimulating hormone secretion
    modifier: DECREASED
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: If the serum fT4 is low, and TSH is low, normal or slightly elevated,
      the diagnosis central CH should be considered
    explanation: The consensus guidelines describe the biochemical pattern of central
      CH reflecting inadequate TSH drive.
  downstream:
  - target: Neurodevelopmental Impairment from Thyroid Hormone Deficiency
    causal_link_type: DIRECT
    description: Inadequate TSH drive results in insufficient thyroid hormone production,
      causing the same downstream neurodevelopmental risk.
    evidence:
    - reference: PMID:29405999
      reference_title: Congenital Hypothyroidism.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Congenital hypothyroidism is common and can cause severe neurodevelopmental
        morbidity.
      explanation: Links thyroid hormone deficiency from any cause to neurodevelopmental
        impairment.
  - target: Prolonged Neonatal Jaundice
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Low TSH drive causes central congenital hypothyroidism.
    description: Central congenital hypothyroidism can present with prolonged neonatal
      jaundice.
    evidence:
    - reference: PMID:33272083
      reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: we recommend endocrine testing in all neonates with a familial history
        of central CH, or signs or symptoms of congenital hypopituitarism, for example,
        micropenis with undescended testes, hypoglycemia, prolonged jaundice, or unexplained
        failure to thrive.
      explanation: The guideline lists prolonged jaundice as a sign prompting testing
        for central congenital hypothyroidism or congenital hypopituitarism.
  - target: Hypotonia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Low TSH drive causes severe central congenital hypothyroidism.
    description: Severe central congenital hypothyroidism can manifest with neonatal
      hypotonia.
    evidence:
    - reference: PMID:33272083
      reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Isolated central CH due to biallelic TSHβ gene mutations is associated
        with severe hypothyroidism and characterized by the typical manifestations
        of CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.).
      explanation: The guideline explicitly lists hypotonia among manifestations
        of severe central congenital hypothyroidism.
  - target: Macroglossia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Low TSH drive causes severe central congenital hypothyroidism.
    description: Severe central congenital hypothyroidism can cause macroglossia.
    evidence:
    - reference: PMID:33272083
      reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Isolated central CH due to biallelic TSHβ gene mutations is associated
        with severe hypothyroidism and characterized by the typical manifestations
        of CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.).
      explanation: The guideline explicitly lists macroglossia among manifestations
        of severe central congenital hypothyroidism.
  - target: Umbilical Hernia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Low TSH drive causes severe central congenital hypothyroidism.
    description: Severe central congenital hypothyroidism can manifest with umbilical
      hernia.
    evidence:
    - reference: PMID:33272083
      reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Isolated central CH due to biallelic TSHβ gene mutations is associated
        with severe hypothyroidism and characterized by the typical manifestations
        of CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.).
      explanation: The guideline explicitly lists umbilical hernia among manifestations
        of severe central congenital hypothyroidism.
- name: Transient Thyroid Dysfunction
  description: Transient congenital hypothyroidism results from reversible disruption
    of thyroid function, most commonly due to transplacental passage of maternal TSH
    receptor-blocking antibodies, exposure to excess iodine, or hypothalamic-pituitary-thyroid
    axis immaturity in premature infants.
  subtypes:
  - Transient
  biological_processes:
  - preferred_term: Thyroid hormone generation
    term:
      id: GO:0006590
      label: thyroid hormone generation
    modifier: DECREASED
  evidence:
  - reference: PMID:20537182
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Transient CH most commonly occurs in preterm infants born in areas of
      endemic iodine deficiency.
    explanation: Identifies prematurity and iodine deficiency as common causes of
      transient CH.
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: the prevalence of transient CH has steadily increased. In a number of
      studies, factors have been identified that increase the likelihood of transient
      disease, such as sex (more often in boys)
    explanation: Guidelines document the increasing prevalence and risk factors for
      transient CH.
  downstream:
  - target: Neurodevelopmental Impairment from Thyroid Hormone Deficiency
    causal_link_type: DIRECT
    description: Even transient thyroid hormone deficiency during critical neonatal
      brain development may cause neurodevelopmental harm if untreated.
    evidence:
    - reference: PMID:29405999
      reference_title: Congenital Hypothyroidism.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Congenital hypothyroidism is common and can cause severe neurodevelopmental
        morbidity.
      explanation: Links thyroid hormone deficiency from any cause to neurodevelopmental
        impairment.
- name: Neurodevelopmental Impairment from Thyroid Hormone Deficiency
  description: Thyroid hormone is indispensable for brain development during fetal
    life and the first 2-3 years. Deficiency during this critical period causes irreversible
    neurodevelopmental damage if untreated, historically known as cretinism.
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: Brain development
    term:
      id: GO:0007420
      label: brain development
    modifier: ABNORMAL
  evidence:
  - reference: PMID:29405999
    reference_title: Congenital Hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Congenital hypothyroidism is common and can cause severe neurodevelopmental
      morbidity.
    explanation: Directly states the neurodevelopmental consequence of congenital
      hypothyroidism.
  - reference: PMID:25729683
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: delayed diagnosis leads to the most severe outcome of CH, mental retardation,
      emphasizing the importance of neonatal screening.
    explanation: Confirms that delayed diagnosis leads to irreversible intellectual
      disability.
  downstream:
  - target: Intellectual Disability
    causal_link_type: DIRECT
    description: Untreated thyroid hormone deficiency during early brain development
      can cause intellectual disability.
    evidence:
    - reference: PMID:25729683
      reference_title: Congenital hypothyroidism.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Congenital hypothyroidism (CH) is the one of the most common preventable
        cause of mental retardation.
      explanation: The review directly identifies intellectual disability as a preventable
        outcome of congenital hypothyroidism.
- name: Iodide Salvage Failure
  biological_scale: MOLECULAR
  description: >-
    Loss of iodotyrosine deiodinase activity removes the control of iodide reuse
    for thyroid hormone synthesis, so the follicular cell loses its
    intrathyroidal iodide recycling. This is the step at which IYD acts, and it
    is separate from iodide transport and from hormone assembly, which is why it
    is modeled as its own node.
  subtypes:
  - Dyshormonogenesis
  locations:
  - preferred_term: thyroid gland
    term:
      id: UBERON:0002046
      label: thyroid gland
  cell_types:
  - preferred_term: thyroid follicular cell
    term:
      id: CL:0002257
      label: epithelial cell of thyroid gland
  genes:
  - preferred_term: IYD
    term:
      id: hgnc:21071
      label: IYD
  molecular_functions:
  - preferred_term: iodotyrosine deiodinase activity
    term:
      id: GO:0140616
      label: iodotyrosine deiodinase activity
    modifier: DECREASED
  evidence:
  - reference: PMID:18434651
    reference_title: Mutations in the iodotyrosine deiodinase gene and hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase."
    explanation: Directly measures the reduced iodotyrosine deiodinase activity this node asserts, in patients with biallelic IYD variants.
  - reference: PMID:18434651
    reference_title: Mutations in the iodotyrosine deiodinase gene and hypothyroidism.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: BACKGROUND
    snippet: "DEHAL1 has been identified as the gene encoding iodotyrosine deiodinase in the thyroid, where it controls the reuse of iodide for thyroid hormone synthesis."
    explanation: States that the enzyme controls iodide reuse in the thyroid, which is the function this node describes as lost.
  downstream:
  - target: Defective Thyroid Hormone Biosynthesis
    causal_link_type: DIRECT
    description: >-
      Without iodide salvage the follicular cell cannot sustain hormone
      synthesis, so the defect converges on the same reduced thyroid hormone
      output as the organification and transport defects.
    evidence:
    - reference: PMID:18434651
      reference_title: Mutations in the iodotyrosine deiodinase gene and hypothyroidism.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Patients had severe goitrous hypothyroidism, which was evident in infancy and childhood."
      explanation: The clinical outcome of the enzyme defect is goitrous hypothyroidism, which is what places this node upstream of defective hormone biosynthesis.
phenotypes:
- category: Clinical
  name: Congenital Hypothyroidism
  description: Thyroid hormone deficiency present at birth, detectable by newborn
    screening.
  phenotype_term:
    preferred_term: Congenital hypothyroidism
    term:
      id: HP:0000851
      label: Congenital hypothyroidism
  diagnostic: true
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The incidence of CH partly depends on the screening strategy; based on
      data from a number of screening programs, the incidence of primary CH lies between
      1 in 3000 and 1 in 2000; the highest reported incidence of central CH is ∼1
      in 16,000
    explanation: Provides the incidence of primary and central congenital hypothyroidism
      from the consensus guidelines.
- category: Clinical
  name: Prolonged Neonatal Jaundice
  description: Prolonged jaundice beyond the first two weeks of life is a common early
    clinical sign of congenital hypothyroidism in neonates.
  phenotype_term:
    preferred_term: Prolonged neonatal jaundice
    term:
      id: HP:0006579
      label: Prolonged neonatal jaundice
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Isolated central CH due to biallelic TSHβ gene mutations is associated
      with severe hypothyroidism and characterized by the typical manifestations of
      CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.).
    explanation: The consensus guidelines list jaundice as a typical manifestation
      of congenital hypothyroidism.
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: we recommend endocrine testing in all neonates with a familial history
      of central CH, or signs or symptoms of congenital hypopituitarism, for example,
      micropenis with undescended testes, hypoglycemia, prolonged jaundice, or unexplained
      failure to thrive.
    explanation: Guidelines specifically mention prolonged jaundice as a clinical
      sign warranting endocrine testing for congenital hypothyroidism.
- category: Clinical
  name: Feeding Difficulties
  description: Feeding difficulties in the neonatal period are an early sign of congenital
    hypothyroidism.
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:20537182
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Common symptoms include decreased activity and increased sleep, feeding
      difficulty, constipation, and prolonged jaundice.
    explanation: Lists feeding difficulty as a common symptom of congenital hypothyroidism.
- category: Clinical
  name: Macroglossia
  description: Enlarged tongue is a classic clinical feature of untreated congenital
    hypothyroidism.
  phenotype_term:
    preferred_term: Macroglossia
    term:
      id: HP:0000158
      label: Macroglossia
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Isolated central CH due to biallelic TSHβ gene mutations is associated
      with severe hypothyroidism and characterized by the typical manifestations of
      CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.).
    explanation: The consensus guidelines explicitly list macroglossia as a typical
      manifestation of congenital hypothyroidism.
- category: Clinical
  name: Hypotonia
  description: Decreased muscle tone is commonly observed in infants with congenital
    hypothyroidism.
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Isolated central CH due to biallelic TSHβ gene mutations is associated
      with severe hypothyroidism and characterized by the typical manifestations of
      CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.).
    explanation: The consensus guidelines explicitly list hypotonia as a typical manifestation
      of congenital hypothyroidism.
- category: Clinical
  name: Intellectual Disability
  description: If untreated, congenital hypothyroidism leads to intellectual disability
    due to the critical role of thyroid hormone in brain development.
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:25729683
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Congenital hypothyroidism (CH) is the one of the most common preventable
      cause of mental retardation.
    explanation: Directly identifies intellectual disability as the most severe preventable
      outcome of untreated congenital hypothyroidism.
- category: Clinical
  name: Short Stature
  description: Growth failure and short stature occur in inadequately treated congenital
    hypothyroidism.
  phenotype_term:
    preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Adequately treated children with nonsyndromic CH have normal growth and
      puberty, and their fertility does not differ from individuals who do not have
      CH
    explanation: Indirectly supports short stature as a phenotype by stating that
      adequately treated CH results in normal growth, implying untreated CH leads
      to growth failure.
- category: Clinical
  name: Goiter
  description: Thyroid enlargement occurs in dyshormonogenesis subtypes where the
    gland is present but hormone synthesis is impaired, and may develop nodules requiring
    monitoring.
  subtype: Dyshormonogenesis
  phenotype_term:
    preferred_term: Goiter
    term:
      id: HP:0000853
      label: Goiter
  evidence:
  - reference: PMID:37390946
    reference_title: Clinical, biochemical characteristics and genotype-phenotype
      analysis of congenital hypothyroidism diagnosed by newborn screening in China.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The "DUOX2 biallelic variants" group was associated with "Goiter"
    explanation: Demonstrates the association of goiter with dyshormonogenesis gene
      variants, specifically DUOX2 biallelic mutations.
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Children and adolescents with primary CH due to dyshomonogenesis may
      develop goiter and nodules; in these cases, serum TSH should be carefully targeted
      in the lower part of normal range and periodical ultrasound investigation is
      recommended to monitor thyroid volume
    explanation: Confirms goiter and nodule development in dyshormonogenesis and recommends
      monitoring.
- category: Clinical
  name: Umbilical Hernia
  description: Umbilical hernia is a classic clinical sign of congenital hypothyroidism
    in newborns.
  phenotype_term:
    preferred_term: Umbilical hernia
    term:
      id: HP:0001537
      label: Umbilical hernia
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Isolated central CH due to biallelic TSHβ gene mutations is associated
      with severe hypothyroidism and characterized by the typical manifestations of
      CH (hypotonia, jaundice, umbilical hernia, macroglossia, etc.).
    explanation: The consensus guidelines explicitly list umbilical hernia as a typical
      manifestation of congenital hypothyroidism.
- category: Clinical
  name: Constipation
  description: Constipation is a common clinical feature in infants with congenital
    hypothyroidism.
  phenotype_term:
    preferred_term: Constipation
    term:
      id: HP:0002019
      label: Constipation
  evidence:
  - reference: PMID:20537182
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Common symptoms include decreased activity and increased sleep, feeding
      difficulty, constipation, and prolonged jaundice.
    explanation: Lists constipation as a common symptom of congenital hypothyroidism.
- category: Clinical
  name: Large Fontanelles
  description: Widely open anterior fontanelle or large posterior fontanelle is a
    classic sign of congenital hypothyroidism in newborns.
  phenotype_term:
    preferred_term: Large fontanelles
    term:
      id: HP:0000239
      label: Large fontanelles
  evidence:
  - reference: PMID:20537182
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: On examination, common signs include myxedematous facies, large fontanels,
      macroglossia, a distended abdomen with umbilical hernia, and hypotonia.
    explanation: Lists large fontanels as a common examination finding in congenital
      hypothyroidism.
- category: Clinical
  name: Dry Skin
  description: Dry, mottled skin is observed in infants with congenital hypothyroidism.
  phenotype_term:
    preferred_term: Dry skin
    term:
      id: HP:0000958
      label: Dry skin
  evidence:
  - reference: PMID:20537182
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: On examination, common signs include myxedematous facies, large fontanels,
      macroglossia, a distended abdomen with umbilical hernia, and hypotonia.
    explanation: Myxedematous facies in CH includes dry, thickened skin characteristic
      of hypothyroidism.
- category: Clinical
  name: Failure to Thrive
  description: Poor weight gain and failure to thrive may be present in untreated
    or undertreated infants with congenital hypothyroidism.
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: we recommend endocrine testing in all neonates with a familial history
      of central CH, or signs or symptoms of congenital hypopituitarism, for example,
      micropenis with undescended testes, hypoglycemia, prolonged jaundice, or unexplained
      failure to thrive.
    explanation: The guidelines identify failure to thrive as a clinical sign prompting
      evaluation for congenital hypothyroidism.
biochemical:
- name: Elevated TSH
  presence: Elevated
  subtype: Permanent Primary
  context: Newborn screening and diagnostic evaluation
  notes: Markedly elevated TSH with low free T4 is the hallmark of primary congenital
    hypothyroidism and the basis of TSH-based newborn screening programs.
  loinc_term:
    id: LOINC:29575-8
    label: Thyrotropin [Units/volume] in DBS
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: the most sensitive test for detecting primary CH is measurement of thyrotropin
      (TSH)
    explanation: Confirms elevated TSH as the primary screening and diagnostic marker
      for primary congenital hypothyroidism.
- name: Low Free Thyroxine
  presence: Decreased
  context: Diagnostic evaluation
  notes: Low serum free T4 is present in all forms of congenital hypothyroidism, whether
    primary or central.
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: If the serum fT4 concentration is below and TSH clearly above the age-specific
      reference interval, then levothyroxine (LT4) treatment should be started immediately
    explanation: Confirms low fT4 as a key diagnostic finding triggering treatment.
genetic:
- name: PAX8
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Permanent Primary
  gene_term:
    preferred_term: PAX8
    term:
      id: hgnc:8622
      label: PAX8
  notes: PAX8 mutations cause thyroid dysgenesis through impaired thyroid gland development.
  evidence:
  - reference: PMID:41303336
    reference_title: 'Molecular Genetics of Primary Congenital Hypothyroidism: Established
      and Emerging Contributors to Thyroid Dysgenesis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Mutations in ten genes involved in thyroid gland development during embryogenesis,
      TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have
      been identified in cohorts of patients with thyroid dysgenesis.
    explanation: Lists PAX8 among the established thyroid dysgenesis genes.
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead
      to thyroid dysgenesis were identified in eight probands.
    explanation: Identifies PAX8 mutations in probands with thyroid dysgenesis in
      a Chinese cohort.
- name: TSHR
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Permanent Primary
  gene_term:
    preferred_term: TSHR
    term:
      id: hgnc:12373
      label: TSHR
  notes: Loss-of-function TSHR mutations cause TSH resistance. TSHR is also classified
    as a thyroid dysgenesis gene.
  evidence:
  - reference: PMID:41303336
    reference_title: 'Molecular Genetics of Primary Congenital Hypothyroidism: Established
      and Emerging Contributors to Thyroid Dysgenesis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Mutations in ten genes involved in thyroid gland development during embryogenesis,
      TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have
      been identified in cohorts of patients with thyroid dysgenesis.
    explanation: Lists TSHR among established thyroid dysgenesis genes.
- name: NKX2-1
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Permanent Primary
  gene_term:
    preferred_term: NKX2-1
    term:
      id: hgnc:11825
      label: NKX2-1
  notes: NKX2-1 (also known as TTF-1) mutations cause thyroid dysgenesis and may be
    associated with brain-lung-thyroid syndrome.
  evidence:
  - reference: PMID:41303336
    reference_title: 'Molecular Genetics of Primary Congenital Hypothyroidism: Established
      and Emerging Contributors to Thyroid Dysgenesis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Mutations in ten genes involved in thyroid gland development during embryogenesis,
      TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have
      been identified in cohorts of patients with thyroid dysgenesis.
    explanation: Lists NKX2-1 among established thyroid dysgenesis genes.
- name: FOXE1
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Permanent Primary
  gene_term:
    preferred_term: FOXE1
    term:
      id: hgnc:3806
      label: FOXE1
  notes: FOXE1 (also known as TTF-2) mutations cause thyroid dysgenesis, often associated
    with cleft palate and choanal atresia (Bamforth-Lazarus syndrome).
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead
      to thyroid dysgenesis were identified in eight probands.
    explanation: Identifies FOXE1 among genes with mutations leading to thyroid dysgenesis.
- name: TPO
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Dyshormonogenesis
  gene_term:
    preferred_term: TPO
    term:
      id: hgnc:12015
      label: TPO
  inheritance:
  - name: Autosomal recessive
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:29650690
      reference_title: The genetic characteristics of congenital hypothyroidism in
        China by comprehensive screening of 21 candidate genes.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Autosomal recessive inheritance of CH caused by mutations in DUOX2,
        DUOXA2, TG and TPO was confirmed by analysis of 22 family pedigrees.
      explanation: Confirms autosomal recessive inheritance for TPO-related CH through
        family pedigree analysis.
  notes: TPO mutations cause impaired iodide organification, leading to goitrous congenital
    hypothyroidism.
  evidence:
  - reference: PMID:37390946
    reference_title: Clinical, biochemical characteristics and genotype-phenotype
      analysis of congenital hypothyroidism diagnosed by newborn screening in China.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: the TSH levels and initial L-T4 dose were significantly higher in "TPO
      biallelic variants" group than those in "DUOX2 and TSHR biallelic variants"
      groups.
    explanation: Demonstrates TPO biallelic variants cause more severe biochemical
      hypothyroidism than DUOX2 or TSHR variants.
- name: DUOX2
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Dyshormonogenesis
  gene_term:
    preferred_term: DUOX2
    term:
      id: hgnc:13273
      label: DUOX2
  inheritance:
  - name: Autosomal recessive
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:29650690
      reference_title: The genetic characteristics of congenital hypothyroidism in
        China by comprehensive screening of 21 candidate genes.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Autosomal recessive inheritance of CH caused by mutations in DUOX2,
        DUOXA2, TG and TPO was confirmed by analysis of 22 family pedigrees.
      explanation: Confirms autosomal recessive inheritance for DUOX2-related CH.
  notes: DUOX2 mutations cause defective hydrogen peroxide generation required for
    thyroid hormone synthesis. DUOX2 is the most frequently mutated gene in CH patients
    in Chinese populations.
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: This study identified previously reported causative genes for 57/110
      Chinese patients and revealed DUOX2 was the most frequently mutated gene in
      these patients.
    explanation: Identifies DUOX2 as the most frequently mutated CH gene in a Chinese
      cohort of 110 patients.
- name: TG
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Dyshormonogenesis
  gene_term:
    preferred_term: TG
    term:
      id: hgnc:11764
      label: TG
  inheritance:
  - name: Autosomal recessive
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:29650690
      reference_title: The genetic characteristics of congenital hypothyroidism in
        China by comprehensive screening of 21 candidate genes.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Autosomal recessive inheritance of CH caused by mutations in DUOX2,
        DUOXA2, TG and TPO was confirmed by analysis of 22 family pedigrees.
      explanation: Confirms autosomal recessive inheritance for TG-related CH.
  notes: Thyroglobulin gene mutations cause defective thyroglobulin synthesis, a substrate
    for thyroid hormone production.
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our results showed that 57 patients (51.82%) carried biallelic mutations
      (containing compound heterozygous mutations and homozygous mutations) in six
      genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone
      synthesis.
    explanation: Identifies TG among the six genes with biallelic mutations in CH
      patients.
- name: SLC5A5
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Dyshormonogenesis
  gene_term:
    preferred_term: SLC5A5
    term:
      id: hgnc:11040
      label: SLC5A5
  notes: SLC5A5 (sodium-iodide symporter) mutations cause defective iodide transport
    into thyroid follicular cells.
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thyroid dyshormonogenesis, which is caused by defects in thyroid hormone
      biosynthesis, accounts for approximately 10–15% of primary CH and is associated
      with the following genes: DUOX2, DUOXA2, DUOX1, TPO, TG, SLC26A4, SLC5A5 and
      TSHR"
    explanation: Explicitly lists SLC5A5 among the genes associated with thyroid
      dyshormonogenesis.
- name: DUOXA2
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Dyshormonogenesis
  gene_term:
    preferred_term: DUOXA2
    term:
      id: hgnc:32698
      label: DUOXA2
  inheritance:
  - name: Autosomal recessive
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:29650690
      reference_title: The genetic characteristics of congenital hypothyroidism in
        China by comprehensive screening of 21 candidate genes.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Autosomal recessive inheritance of CH caused by mutations in DUOX2,
        DUOXA2, TG and TPO was confirmed by analysis of 22 family pedigrees.
      explanation: Confirms autosomal recessive inheritance for DUOXA2-related CH.
  notes: DUOXA2 is a maturation factor for DUOX2, required for proper DUOX2 function
    in hydrogen peroxide generation for thyroid hormone synthesis.
  evidence:
  - reference: PMID:29650690
    reference_title: The genetic characteristics of congenital hypothyroidism in China
      by comprehensive screening of 21 candidate genes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our results showed that 57 patients (51.82%) carried biallelic mutations
      (containing compound heterozygous mutations and homozygous mutations) in six
      genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone
      synthesis.
    explanation: Identifies DUOXA2 among the six genes with biallelic mutations
      in thyroid hormone synthesis in CH patients.
- name: SLC26A4
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Dyshormonogenesis
  gene_term:
    preferred_term: SLC26A4
    term:
      id: hgnc:8818
      label: SLC26A4
  notes: SLC26A4 (pendrin) mutations cause Pendred syndrome with goiter, congenital
    hypothyroidism, and sensorineural hearing loss.
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Pendred syndrome due to mutations in the SLC26A4 gene (OMIM No. 274600),
      with or without goiter, should be considered in case of congenital sensorineural
      hearing loss.
    explanation: Guidelines identify SLC26A4 as a cause of syndromic CH (Pendred
      syndrome) with hearing loss and goiter.
- name: NKX2-5
  relationship_type: SUSCEPTIBILITY
  presence: Present
  subtype: Permanent Primary
  gene_term:
    preferred_term: NKX2-5
    term:
      id: hgnc:2488
      label: NKX2-5
  notes: >-
    MONDO assigns hypothyroidism, congenital, nongoitrous, 5 (MONDO:0009154) to
    NKX2-5, and a recent narrative review lists NKX2-5 among ten genes with
    mutations identified in thyroid dysgenesis cohorts. The primary evidence is
    thin and contested, so this record is typed SUSCEPTIBILITY rather than
    CAUSATIVE: the original study found three heterozygous missense changes in
    four of 241 patients and called the role previously unknown, and a later
    screen of 63 Brazilian children with thyroid dysgenesis found no mutations in
    NKX2-5. The ClinGen Gene-Disease Validity table lists no NKX2-5 assertion
    for congenital
    hypothyroidism or thyroid dysgenesis (checked 2026-09-25).
  inheritance:
  - name: Autosomal dominant
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  evidence:
  - reference: PMID:16418214
    reference_title: "Missense mutation in the transcription factor NKX2-5: a novel molecular event in the pathogenesis of thyroid dysgenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "NKX2-5 mutational screening in 241 patients with TD allowed the identification of three heterozygous missense changes (R25C, A119S, and R161P) in four patients with TD."
    explanation: The primary human genetic observation behind the NKX2-5 assignment, and the source of the counts in these notes.
  - reference: PMID:16418214
    reference_title: "Missense mutation in the transcription factor NKX2-5: a novel molecular event in the pathogenesis of thyroid dysgenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our results suggest a previously unknown role of NKX2-5 in the pathogenesis of TD."
    explanation: The authors' own hedged conclusion, quoted so this record does not read as an established gene-disease relationship.
  - reference: PMID:30304112
    reference_title: "Mutation screening in the genes PAX-8, NKX2-5, TSH-R, HES-1 in cohort of 63 Brazilian children with thyroid dysgenesis."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "No mutations were detected in any of the candidate genes."
    explanation: A negative NKX2-5 screen in 63 children with thyroid dysgenesis, which is the reason this record is typed SUSCEPTIBILITY. It does not exclude NKX2-5 in individual families.
  - reference: PMID:41303336
    reference_title: 'Molecular Genetics of Primary Congenital Hypothyroidism: Established
      and Emerging Contributors to Thyroid Dysgenesis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Mutations in ten genes involved in thyroid gland development during embryogenesis,
      TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, and TUBB1, have
      been identified in cohorts of patients with thyroid dysgenesis.
    explanation: Lists NKX2-5 among the thyroid dysgenesis genes in a 2025 review of the field.
- name: IYD
  relationship_type: CAUSATIVE
  presence: Present
  subtype: Dyshormonogenesis
  gene_term:
    preferred_term: IYD
    term:
      id: hgnc:21071
      label: IYD
  notes: >-
    IYD, for which HGNC records DEHAL1 as an alias, encodes iodotyrosine
    deiodinase. Biallelic variants cause thyroid dyshormonogenesis 4 by removing
    the iodide rescue and recycling step rather than a step of hormone assembly,
    which is why it is wired to its own pathophysiology node upstream of
    defective hormone biosynthesis. The ClinGen Gene-Disease Validity table lists no IYD
    assertion (checked 2026-09-25).
  inheritance:
  - name: Autosomal recessive
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:28648508
      reference_title: Iodide handling disorders (NIS, TPO, TG, IYD).
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "These mutations produce a heterogeneous spectrum of CH, with an autosomal recessive inheritance."
      explanation: States autosomal recessive inheritance for the iodide-handling dyshormonogenesis genes, IYD among them.
  evidence:
  - reference: PMID:18434651
    reference_title: Mutations in the iodotyrosine deiodinase gene and hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase."
    explanation: Establishes biallelic IYD variants with reduced enzyme activity in four patients from three families.
  - reference: PMID:18434651
    reference_title: Mutations in the iodotyrosine deiodinase gene and hypothyroidism.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: BACKGROUND
    snippet: "DEHAL1 has been identified as the gene encoding iodotyrosine deiodinase in the thyroid, where it controls the reuse of iodide for thyroid hormone synthesis."
    explanation: States the iodide-reuse function of the gene product. The sentence reports a previously established gene assignment rather than a result of this study.
  - reference: PMID:28648508
    reference_title: Iodide handling disorders (NIS, TPO, TG, IYD).
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: "TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes."
    explanation: Names IYD among the genes in which mutations cause thyroid dyshormonogenesis.
treatments:
- name: Levothyroxine Replacement
  description: Levothyroxine is the standard treatment for congenital hypothyroidism.
    Early initiation within 2 weeks of birth at doses of 10-15 mcg/kg/day is critical
    to prevent irreversible neurodevelopmental damage.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: levothyroxine
      term:
        id: CHEBI:6446
        label: levothyroxine sodium anhydrous
  target_phenotypes:
  - preferred_term: Congenital hypothyroidism
    term:
      id: HP:0000851
      label: Congenital hypothyroidism
  target_mechanisms:
  - target: Neurodevelopmental Impairment from Thyroid Hormone Deficiency
    treatment_effect: MODULATES
    description: Exogenous levothyroxine bypasses the endogenous thyroid hormone deficiency,
      preventing neurodevelopmental impairment when started early.
    evidence:
    - reference: PMID:29405999
      reference_title: Congenital Hypothyroidism.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Early and adequate treatment with levothyroxine results in excellent
        neurodevelopmental outcomes for most patients with congenital hypothyroidism.
      explanation: Directly supports the efficacy of early levothyroxine treatment
        in preventing neurodevelopmental morbidity.
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: LT4 treatment should be started as soon as possible, not later than 2
      weeks after birth or immediately after confirmatory (serum) thyroid function
      testing
    explanation: Consensus guideline recommendation for early levothyroxine treatment.
  - reference: PMID:25729683
    reference_title: Congenital hypothyroidism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Treatment should be started promptly and infant should be rendered euthyroid
      as early as possible, as there is an inverse relationship between intelligence
      quotient (IQ) and the age at diagnosis.
    explanation: Demonstrates the critical importance of early treatment with the
      inverse IQ-diagnosis age relationship.
- name: Newborn Screening
  description: Universal newborn screening programs detect congenital hypothyroidism
    through TSH and/or T4 measurement from heel-prick dried blood spots, enabling
    early treatment before clinical symptoms develop.
  treatment_term:
    preferred_term: disease screening
    term:
      id: NCIT:C15419
      label: Disease Screening
  target_phenotypes:
  - preferred_term: Congenital hypothyroidism
    term:
      id: HP:0000851
      label: Congenital hypothyroidism
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Early detection and treatment of CH through neonatal screening prevent
      irreversible neurodevelopmental delay and optimize its developmental outcome
    explanation: Strong recommendation for universal newborn screening from the consensus
      guidelines.
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Neonatal screening for CH has almost eliminated the profound negative
      effects of TH deficiency on growth and neurodevelopment (cretinism) in those
      countries where it has been established.
    explanation: Documents the public health success of newborn screening in preventing
      cretinism.
- name: Genetic Counseling
  description: Targeted genetic counseling for families with congenital hypothyroidism,
    particularly for dyshormonogenesis (25% recurrence risk for autosomal recessive
    forms) and familial thyroid dysgenesis.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Counseling should include explaining inheritance and the risk of recurrence
      of the patient's primary or central form of CH, based on the CH subtype, the
      family history, and, if known, the (genetic) cause
    explanation: Guideline recommendation for targeted genetic counseling in CH families.
diagnosis:
- name: Newborn screening (TSH-based)
  description: Universal newborn screening using TSH measurement from dried blood
    spots collected 48 hours after birth is the primary method of detecting primary
    congenital hypothyroidism.
  diagnosis_term:
    preferred_term: disease screening
    term:
      id: NCIT:C15419
      label: Disease Screening
  measurements:
  - preferred_term: TSH, DBS
    term:
      id: LOINC:29575-8
      label: Thyrotropin [Units/volume] in DBS
  reference_ranges:
  - loinc_term:
      id: LOINC:29575-8
      label: Thyrotropin [Units/volume] in DBS
    unit: m[IU]/L
    population: newborn screening, Republic of Ireland national programme (whole-blood TSH, since 1979)
    notes: >-
      Source wording: "The NBS programme in the Republic of Ireland has used a cut-off of
      8 mU/L since 1979." Whole-blood (dried-blood-spot) TSH in mU/L; the source itself
      notes there is no consensus on the optimal screening cut-off, so this band records
      Ireland's threshold rather than a universal one.
    interpretation_bands:
    - name: Screen negative
      upper_bound: 8
      unit: m[IU]/L
      abnormal_flag: NORMAL
    - name: Screen positive
      lower_bound: 8
      unit: m[IU]/L
      abnormal_flag: HIGH
      interpretation: >-
        Whole-blood TSH at or above the programme cut-off is a presumptive positive
        screen for primary congenital hypothyroidism and leads to confirmatory serum
        TSH and free T4.
    evidence:
    - reference: PMID:29804122
      reference_title: "Permanent Decompensated Congenital Hypothyroidism in Newborns with Whole-Blood Thyroid-Stimulating Hormone Concentrations between 8 and 10 mU/L: The Case for Lowering the Threshold."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The NBS programme in the Republic of Ireland has used a cut-off of 8 mU/L since 1979."
      explanation: >-
        States the whole-blood TSH screening cut-off used by the Irish national
        programme.
  - loinc_term:
      id: LOINC:29575-8
      label: Thyrotropin [Units/volume] in DBS
    unit: m[IU]/L
    population: newborn screening, Republic of Macedonia national programme (DELFIA fluoroimmunoassay, dried blood spot)
    notes: >-
      Source wording: "The TSH cutoff level was 10 mU/L blood." Recorded as a second
      programme's cut-off; 10 mU/L is also the level several other programmes in the
      searched literature report, but each is cited only where its own paper states it.
    interpretation_bands:
    - name: Screen negative
      upper_bound: 10
      unit: m[IU]/L
      abnormal_flag: NORMAL
    - name: Screen positive
      lower_bound: 10
      unit: m[IU]/L
      abnormal_flag: HIGH
      interpretation: >-
        Dried-blood-spot TSH at or above the programme cut-off led to recall for
        confirmatory testing.
    evidence:
    - reference: PMID:25192932
      reference_title: "Clinical practice: experience with newborn screening for congenital hypothyroidism in the Republic of Macedonia - a multiethnic country."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The TSH cutoff level was 10 mU/L blood."
      explanation: >-
        States the dried-blood-spot TSH cut-off of the Macedonian national programme.
  notes: >-
    LOINC codes and labels were read from the Monarch KG and seeded into
    cache/loinc/terms.csv by scripts/seed_loinc_cache.sh. LOINC's only quantitative
    DBS thyrotropin code is Thyrotropin [Units/volume] in DBS (LOINC:29575-8), which
    matches the mU/L of both cited programmes; the unit is written in UCUM as m[IU]/L.
    This row is the TSH-primary strategy; programmes that screen T4-first use a
    different analyte (Thyroxine (T4) [Mass/volume] in DBS, LOINC:31144-9) and are not
    bound here because the entry's screening row and cited sources are TSH-based.
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Early detection and treatment of CH through neonatal screening prevent
      irreversible neurodevelopmental delay and optimize its developmental outcome
    explanation: Strong recommendation for universal newborn screening from consensus
      guidelines.
  - reference: PMID:25192932
    reference_title: "Clinical practice: experience with newborn screening for congenital hypothyroidism in the Republic of Macedonia - a multiethnic country."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we measured thyroid-stimulating hormone (TSH) levels in dried blood spot specimens using the DELFIA fluoroimmunoassay, over a period of 12 years."
    explanation: >-
      A national programme measuring dried-blood-spot TSH as the screening
      measurement for congenital hypothyroidism.
- name: Confirmatory serum thyroid function testing
  description: Confirmatory measurement of serum fT4 and TSH is required after an
    abnormal screening result. If serum TSH is >20 mU/L, treatment should start even
    if fT4 is normal.
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: If the serum fT4 concentration is below and TSH clearly above the age-specific
      reference interval, then levothyroxine (LT4) treatment should be started immediately
    explanation: Guidelines specify the confirmatory testing criteria for initiating
      treatment.
- name: Thyroid imaging
  description: Thyroid scintigraphy and/or ultrasonography to determine thyroid morphology
    (dysgenesis vs gland in situ), which informs the etiology and prognosis.
  diagnosis_term:
    preferred_term: nuclear medicine imaging procedure
    term:
      id: NCIT:C62667
      label: Radionuclide Imaging
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We recommend imaging of the thyroid gland using either radioisotope scanning
      (scintigraphy) with or without the perchlorate discharge test, or ultrasonography
      (US), or both
    explanation: Guidelines recommend thyroid imaging to determine the etiology of CH.
- name: Genetic testing
  description: Molecular genetic testing to identify causative mutations, particularly
    for dyshormonogenesis genes and thyroid dysgenesis transcription factors, informing
    genetic counseling.
  diagnosis_term:
    preferred_term: genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  evidence:
  - reference: PMID:33272083
    reference_title: "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: If genetic testing is performed, its aim should be improving diagnosis,
      treatment, or prognosis
    explanation: Guidelines support genetic testing when it informs clinical management.
computational_models:
- name: Minimal Hypothalamic-Pituitary-Thyroid Feedback Model
  description: >-
    A minimal two-state (TSH, free T4) ODE model of the
    hypothalamic-pituitary-thyroid negative-feedback loop, authored for
    dismech-perturb (analogous to
    the hand-authored CKD-MBD Antimony component; not a BioModels deposit).
    Pituitary TSH output is suppressed by free T4; the thyroid secretes T4 in
    proportion to TSH scaled by secretory capacity S_thy. Calibrated to a
    euthyroid steady state (TSH ~1.5 mU/L, free T4 ~15 pmol/L). Reducing S_thy
    reproduces primary congenital hypothyroidism (dysgenesis / dyshormonogenesis)
    with the compensatory TSH rise; reducing pituitary capacity reproduces
    central hypothyroidism (low free T4 with inappropriately normal TSH); and
    the exogenous levothyroxine term (LT4) restores euthyroidism, with
    over-replacement driving iatrogenic thyrotoxicosis.
  model_type: KINETIC
  model_id: hpt_feedback_axis
  model_format: SBML
  model_software: Antimony/tellurium
  perturbations:
  - preferred_term: TPO
    term:
      id: hgnc:12015
      label: TPO
  - preferred_term: TG
    term:
      id: hgnc:11764
      label: TG
  - preferred_term: DUOX2
    term:
      id: hgnc:13273
      label: DUOX2
  - preferred_term: SLC5A5
    term:
      id: hgnc:11040
      label: SLC5A5
  - preferred_term: TSHR
    term:
      id: hgnc:12373
      label: TSHR
  - preferred_term: PAX8
    term:
      id: hgnc:8622
      label: PAX8
  - preferred_term: NKX2-1
    term:
      id: hgnc:11825
      label: NKX2-1
  - preferred_term: FOXE1
    term:
      id: hgnc:3806
      label: FOXE1
  modeled_mechanisms:
  - target: Defective Thyroid Hormone Biosynthesis
    description: >-
      Reduced thyroid secretory capacity S_thy captures dyshormonogenesis (TPO,
      TG, DUOX2, SLC5A5 defects); the compensatory TSH rise is emergent from the
      feedback loop.
  - target: Thyroid Gland Dysgenesis
    description: >-
      Severe reduction of S_thy captures thyroid agenesis/hypoplasia (PAX8,
      NKX2-1, FOXE1, TSHR defects), yielding low free T4 and markedly elevated
      TSH.
  - target: Impaired Hypothalamic-Pituitary TSH Drive
    description: >-
      Reduced pituitary capacity P_pit reproduces central hypothyroidism: low
      free T4 with inappropriately normal (non-elevated) TSH, the feature that
      distinguishes it from primary hypothyroidism.
  evidence:
  - reference: PMID:18844475
    reference_title: "Extensions, validation, and clinical applications of a feedback control system simulator of the hypothalamo-pituitary-thyroid axis."
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: >-
      feedback control system (FBCS) simulation model of human thyroid hormone
      (TH) regulation to include explicit representation of hypothalamic and
      pituitary dynamics
    explanation: >-
      Establishes the validated feedback-control-simulator approach to the HPT
      axis that this minimal two-state model encodes in reduced form.
  findings:
  - statement: >-
      Central hypothyroidism is modeled by reducing pituitary TSH secretion,
      producing low thyroid hormone with non-elevated TSH - the P_pit
      perturbation in this model.
    evidence:
    - reference: PMID:18844475
      reference_title: "Extensions, validation, and clinical applications of a feedback control system simulator of the hypothalamo-pituitary-thyroid axis."
      supports: SUPPORT
      evidence_source: COMPUTATIONAL
      snippet: >-
        We simulated steady-state plasma T(3), T(4), and TSH concentrations in
        response to varying degrees of central hypothyroidism, reducing TSH
        secretion from 50% down to 0.1% of normal
      explanation: >-
        Confirms that reducing pituitary TSH secretion is the accepted way to
        simulate central hypothyroidism, matching this model's P_pit perturbation.
  - statement: >-
      Levothyroxine replacement normalizes the thyroid axis in the simulator,
      the basis for the model's levothyroxine (LT4) treatment scenarios.
    evidence:
    - reference: PMID:18844475
      reference_title: "Extensions, validation, and clinical applications of a feedback control system simulator of the hypothalamo-pituitary-thyroid axis."
      supports: SUPPORT
      evidence_source: COMPUTATIONAL
      snippet: >-
        We then explored three contemporary clinical issues with the new model:
        combined triiodothyronine (T(3))/thyroxine (T(4)) versus T(4)-only
        treatment, parenteral levothyroxine (L-T(4)) administration, and central
        hypothyroidism
      explanation: >-
        Shows the simulator is used to study levothyroxine (L-T4) replacement,
        the treatment reproduced by this model's LT4 scenarios.
  notes: >-
    Wired for dismech-perturb (models/hpt_feedback_axis/config.yaml; Antimony
    source models/hpt_feedback_axis/model.ant). The disease-severity dial is thyroid
    secretory capacity S_thy (baseline_gfr 1.0 = normal). Levothyroxine is an
    exogenous, TSH-independent T4 source (LT4); treatment scenarios titrate it
    from under-replacement (residual high TSH) through full replacement
    (euthyroid) to over-replacement (suppressed TSH, elevated free T4 =
    iatrogenic thyrotoxicosis). Thresholds are calibrated to model steady-state
    values, not clinical assay reference ranges.
  variables:
  - name: TSH
    dataset_identifier: TSH
    description: >-
      Plasma thyroid-stimulating hormone at steady state; rises as thyroid
      secretory capacity falls (primary hypothyroidism) and is suppressed by
      levothyroxine over-replacement.
    unit: mU/L
    mappings_list:
    - preferred_term: Elevated circulating thyroid-stimulating hormone concentration
      description: >-
        Elevated steady-state TSH from loss of thyroid hormone negative feedback.
        Threshold calibrated to the model (euthyroid ~1.5 mU/L).
      term:
        id: HP:0002925
        label: Elevated circulating thyroid-stimulating hormone concentration
      threshold: 4.0
      threshold_direction: above
      severity_scale:
      - threshold: 4.0
        name: mild
      - threshold: 10.0
        name: moderate
      - threshold: 20.0
        name: severe
  - name: FT4
    dataset_identifier: FT4
    description: >-
      Free thyroxine at steady state; falls in primary and central
      hypothyroidism and rises above normal with levothyroxine over-replacement.
    unit: pmol/L
    mappings_list:
    - preferred_term: Hypothyroidism
      description: >-
        Low free T4 relative to the euthyroid baseline (~15 pmol/L). Evaluated as
        a ratio to baseline; bands calibrated to the model, not assay ranges.
      term:
        id: HP:0000821
        label: Hypothyroidism
      threshold: 0.85
      threshold_direction: below
      severity_scale:
      - threshold: 0.85
        name: mild
      - threshold: 0.7
        name: moderate
      - threshold: 0.55
        name: severe
    - preferred_term: Hyperthyroidism
      description: >-
        Free T4 above the euthyroid range, modeling iatrogenic thyrotoxicosis
        from levothyroxine over-replacement. Threshold calibrated to the model.
      term:
        id: HP:0000836
        label: Hyperthyroidism
      threshold: 20.0
      threshold_direction: above
      severity_scale:
      - threshold: 20.0
        name: mild
      - threshold: 24.0
        name: moderate
      - threshold: 30.0
        name: severe
datasets:
- accession: geo:GSE161041
  title: Epigenome wide Association and Stochastic Epigenetic Mutation analysis on 23 twin pairs heterogeneously affected by Congenital Hypothyroidism (CH).
  description: We performed a whole-genome DNA methylation analysis (Infinium HumanMethylation450 BeadChip) on peripheral whole blood of 23 twin pairs (10 monozygotic and 13 dizygotic) heterogeneously (4 concordant and 19 discordant) affected by Congenital Hypothyroidism (CH) at birth.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: METHYLATION
  sample_count: 46
  publication: PMID:36071330
  notes: Identified by GEO DataSets index search for Congenital Hypothyroidism (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
- accession: geo:GSE18152
  title: Screening for chromosomal aberrations by array CGH in 74 patients with congenital hypothyroidism
  description: Congenital Hypothyroidism occurs in 1:3500 live births and is therefore the most common congenital endocrine disorder. A spectrum of defective thyroid morphology, termed thyroid dysgenesis, represents 80% of permanent CH cases. Although several candidate genes have been implicated in thyroid development, comprehensive screens failed to detect mutation carriers in a significant number of patients with non-syndromic TD. Due to the sporadic occurrence of TD, de novo chromosomal rearrangements are conceivably representing one of the molecular mechanisms participating in its aetiology.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  sample_count: 80
  publication: PMID:20427504
  notes: Identified by GEO DataSets index search for Congenital Hypothyroidism (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
📚

References & Deep Research

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Congenital Hypothyroidism — Manual Literature Research ▸

Congenital Hypothyroidism — Manual Literature Research

Research Method

Manual PubMed search and literature review (no deep research API keys available). Searched PubMed for: congenital hypothyroidism review, thyroid dysgenesis genetics, thyroid dyshormonogenesis, newborn screening, levothyroxine treatment outcomes.

Key References Used

  1. PMID:33272083 — van Trotsenburg et al. (2021) "Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update" — ENDO-ERN consensus guidelines. Comprehensive coverage of screening, diagnosis, treatment, and genetics.

  2. PMID:29405999 — Wassner (2018) "Congenital Hypothyroidism" — Review covering etiology (dysgenesis vs dyshormonogenesis), screening, and treatment.

  3. PMID:25729683 — Agrawal et al. (2015) "Congenital hypothyroidism" — Review covering epidemiology (85% dysgenesis, 15% dyshormonogenesis), clinical features, screening, treatment.

  4. PMID:41303336 — Dermitzaki et al. (2025) "Molecular Genetics of Primary Congenital Hypothyroidism: Established and Emerging Contributors to Thyroid Dysgenesis" — Review of 10 established TD genes (TSHR, PAX8, NKX2-1, NKX2-5, FOXE1, JAG1, NTN1, GLIS3, CDC8A, TUBB1).

  5. PMID:29650690 — Sun et al. (2018) "The genetic characteristics of congenital hypothyroidism in China" — NGS of 21 genes in 110 patients showing DUOX2 most frequently mutated; dyshormonogenesis predominant in Chinese population.

  6. PMID:37390946 — Zhang et al. (2023) "Clinical, biochemical characteristics and genotype-phenotype analysis" — DUOX2 highest variant rate, followed by TG, TPO, TSHR.

Key Facts

  • Incidence: 1:2000–1:3000 for primary CH; ~1:16,000 for central CH
  • Thyroid dysgenesis accounts for 65–85% of primary CH cases
  • Dyshormonogenesis accounts for 15–35% (higher in some populations)
  • Category: Complex (both genetic and environmental/iodine factors)
  • Newborn screening has nearly eliminated cretinism where implemented
  • Early levothyroxine treatment (within 2 weeks) is critical for neurodevelopment