Dyskeratosis Congenita

Mendelian MONDO:0015780 Pathograph 44 Show in embeddings browser Bone Marrow Failure Inherited Bone Marrow Failure Syndrome Telomere Biology Disorder

Dyskeratosis congenita (DC) is a rare inherited multisystem telomere biology disorder (TBD) caused by impaired telomere maintenance resulting in abnormally short or dysfunctional telomeres. Classic DC is defined by a mucocutaneous triad of dysplastic nails, lacy reticular skin pigmentation, and oral leukoplakia, and is complicated by progressive bone marrow failure, predisposition to myelodysplastic syndrome / acute myeloid leukemia and squamous cell carcinoma, and pulmonary and hepatic fibrosis. DC sits at the early-onset, classic end of the broader telomere biology disorder spectrum, with Hoyeraal-Hreidarsson syndrome (with cerebellar hypoplasia) and Revesz syndrome (with exudative retinopathy) representing severe variants. Pathogenic germline variants in at least 16 genes spanning the telomerase core (TERT, TERC), the H/ACA snoRNP (DKC1, NHP2, NOP10, NAF1), telomerase trafficking (WRAP53), the shelterin complex (TINF2, ACD, POT1), the CST replication complex (CTC1, STN1, RPA1), the RTEL1 helicase, and RNA-processing factors (PARN, ZCCHC8) cause DC, with X-linked, autosomal dominant, and autosomal recessive inheritance depending on the gene. Diagnosis relies on multicolor flow-FISH lymphocyte telomere length testing (very short telomeres, often below the 1st percentile for age) and germline genetic testing, which identifies a pathogenic variant in approximately 80% of clinically diagnosed individuals. At the opposite, adult end of the same spectrum sit the numbered telomere-related pulmonary fibrosis / bone marrow failure entities, in which dominant variants in the same genes present decades later with lung disease rather than the mucocutaneous triad; the POT1 member of that series (PFBMFT8) is curated here as a subtype alongside the recessive POT1 form.

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Classifications

IUIS Category

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Inheritance

X-linked recessive inheritance HP:0001419

X-linked recessive inheritance applies to DKC1, the gene encoding dyskerin and historically the most common and most severe form of classic DC.

X-linked recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"The mode of inheritance of DC/TBD varies by gene: X-linked: DKC1."

GeneReviews assigns X-linked inheritance specifically to DKC1.

Autosomal dominant inheritance HP:0000006

Autosomal dominant inheritance applies to NAF1, RPA1, TERC, TINF2, and ZCCHC8, and is the most frequent mode in adult-onset (cryptic) TBD.

Autosomal dominant inheritance

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."

GeneReviews lists the autosomal dominant DC/TBD genes.

PMID:38066848 SUPPORT Human Clinical

"TBD genetic etiology includes all modes of inheritance, with autosomal dominant the most frequent in adult-onset disease."

Autosomal dominant inheritance predominates in adult-onset TBD.

Autosomal recessive inheritance HP:0000007

Autosomal recessive inheritance applies to CTC1, NHP2, NOP10, POT1, STN1, and WRAP53; ACD, PARN, RTEL1, and TERT can be inherited as either dominant or recessive.

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."

GeneReviews lists the autosomal recessive DC/TBD genes.

Digenic inheritance HP:0010984

Digenic inheritance applies to the TYMS-ENOSF1 form, in which a germline TYMS coding variant inherited from one parent and a haplotype with rare variants in the TYMS antisense regulator ENOSF1 inherited from the other are both required. The pedigrees look recessive, but carriers of either variant alone are unaffected, so this is not autosomal recessive transmission at a single locus. The contributing genes are curated as the DKCD subtype and as the TYMS and ENOSF1 records in the genetic section.

Digenic inheritance

Show evidence (2 references)

PMID:35931051 SUPPORT Human Clinical

"These cell and molecular abnormalities generated by the combination of germline digenic variants at the TYMS-ENOSF1 locus represent a unique pathogenetic pathway for DC causation in these affected individuals, whereas the parents who are carriers of either of these variants in a singular fashion..."

States the two-locus requirement and the unaffected single-variant carrier parents, which is what the HPO digenic inheritance term asserts.

PMID:35931051 SUPPORT Human Clinical

"Although the inheritance appeared to be autosomal recessive, one parent in each family had a wild-type TYMS coding sequence."

Records why the pedigrees read as recessive while the transmission is digenic.

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Subtypes

X-linked DC (DKC1, dyskerin) MONDO:0010584 MONDO:0100152

DKC1 hgnc:2890 X-linked recessive inheritance MONDO MONDO:0100152

X-linked recessive DC caused by pathogenic variants in DKC1 encoding dyskerin, a core component of the H/ACA small nucleolar ribonucleoprotein required for pseudouridylation and for stability of the telomerase RNA component. DKC1 disease is historically the most common and most severe classic DC form, including Hoyeraal-Hreidarsson syndrome.

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"The mode of inheritance of DC/TBD varies by gene: X-linked: DKC1."

GeneReviews assigns X-linked inheritance to DKC1.

CGGV:assertion_bb90bea1-16e7-44da-8551-91fb5fd7088a-2025-09-22T170000.000Z SUPPORT Other

ClinGen curated DKC1 against the same X-linked dyskeratosis congenita class bound as this subtype's subtype_term, and classifies the relationship as Definitive.

Telomerase reverse transcriptase (TERT) MONDO:0013521

TERT hgnc:11730 Autosomal dominant inheritance Autosomal recessive inheritance MONDO MONDO:0013521

DC caused by variants in TERT, the catalytic protein subunit of telomerase. TERT-associated disease can be inherited as autosomal dominant or autosomal recessive and is a common cause of adult-onset/cryptic TBD with pulmonary or hepatic fibrosis.

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."

GeneReviews lists TERT as dominant or recessive DC/TBD.

CGGV:assertion_afb6ea76-e8ac-4a38-b42c-23fc18a9623b-2020-07-30T205843.081Z SUPPORT Other

ClinGen curated TERT against the numbered dominant class mapped on this subtype and classifies the relationship as Definitive, under semidominant inheritance.

Telomerase RNA component (TERC) MONDO:0007485

TERC hgnc:11727 Autosomal dominant inheritance

Autosomal dominant DC caused by variants in TERC, the RNA template subunit of telomerase. Frequently underlies later-onset disease with pulmonary fibrosis.

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."

GeneReviews lists TERC as autosomal dominant DC/TBD.

CGGV:assertion_cfdf86d0-9441-40bf-a1da-ab2c85f775cd-2024-11-25T170000.000Z SUPPORT Other

ClinGen curated TERC against the numbered dominant class bound as this subtype's subtype_term, under autosomal dominant inheritance, and classifies the relationship as Definitive.

Dyskeratosis congenita, autosomal dominant 3 (DKCA3; shelterin TINF2/TIN2) MONDO:0013522

TINF2 hgnc:11824 Autosomal dominant inheritance

Autosomal dominant DC caused by variants in TINF2 encoding the shelterin component TIN2, and the numbered designation DKCA3 (OMIM 613990). TINF2 disease is often severe and early-onset, and is enriched for severe variants including Revesz syndrome and progression to liver disease. TINF2 was found in 2008 by linkage in a family with autosomal dominant DC in which DKC1, TERC and TERT had already been excluded. The founding report identified K280E in a proband and five affected relatives, R282H in three further unrelated probands and R282S in a fifth, found none of them in unaffected relatives or in 298 controls, and so made TINF2 the first shelterin component linked to human disease. The narrow clustering of those alleles is the feature that carries through the rest of the TINF2 literature: the pathogenic variants sit in a short stretch of exon 6, and the severe phenotypes at the Revesz end of the spectrum come from the same window.

Show evidence (8 references)

PMID:37184208 SUPPORT Human Clinical

"those with heterozygous TINF2 DC were significantly younger, predominantly male, and more likely to have DC-associated mucocutaneous triad features and severe bone marrow failure"

TINF2 DC patients are younger with severe triad features and bone marrow failure.

CGGV:assertion_b32866f2-6fa1-4a63-9624-3588d0811ea7-2025-02-20T170000.000Z SUPPORT Other

The identifier this row now binds, with ClinGen's classification of the gene-disease relationship as Definitive and - the part the lump/split call turns on - its mode of inheritance as AD.

CGGV:assertion_b32866f2-6fa1-4a63-9624-3588d0811ea7-2025-02-20T170000.000Z SUPPORT REVIEW SYNTHESIS Other

"TINF2 was first reported in relation to dyskeratosis congenita, autosomal dominant 3 (MONDO: 0013522) in 2008 (Savage et al., 2008 PMID: 18252230)."

Ties the MONDO identifier bound here to the founding TINF2 report, which is what makes DKCA3 the numbered designation for this row's disease rather than a neighbouring concept. quote_role REVIEW_SYNTHESIS because this sentence is ClinGen attributing someone else's finding, unlike the lumping decision two items down, which is ClinGen's own product.

+ 5 more references

Regulator of telomere elongation helicase 1 (RTEL1) MONDO:0014076

RTEL1 hgnc:15888 Autosomal dominant inheritance Autosomal recessive inheritance MONDO MONDO:0014076

DC caused by variants in RTEL1, a DNA helicase that dismantles telomeric T-loops and supports telomere replication. RTEL1 disease can be autosomal dominant or recessive and includes Hoyeraal-Hreidarsson syndrome.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."

GeneReviews lists RTEL1 as dominant or recessive DC/TBD.

RTEL1-related pulmonary fibrosis and/or bone marrow failure, telomere-related, 3 MONDO:0014613

RTEL1 hgnc:15888 Autosomal dominant inheritance

The adult, pulmonary-predominant RTEL1 presentation, and the third locus of the numbered telomere-related pulmonary fibrosis / bone marrow failure series (OMIM 616373). It is the dominant, later-onset half of a gene whose recessive half is Hoyeraal-Hreidarsson syndrome and severe childhood DC, and it is defined by two 2015 exome studies of familial pulmonary fibrosis. In the larger of the two, heterozygous rare RTEL1 variants segregated with familial interstitial pneumonia in nine of 188 kindreds - one of the original 25 exome families and eight of a further 163 - a yield of about five percent. The second study found RTEL1 significantly enriched for new damaging and missense variants at conserved residues in familial pulmonary fibrosis cases against 2,816 controls, and put RTEL1 and PARN together at roughly seven percent of familial pulmonary fibrosis. Two features distinguish this subtype from the gene-level RTEL1 row above rather than merely renaming it. Penetrance is incomplete in a way the childhood presentations are not: unaffected carriers in these families have short telomeres too, so the short-telomere phenotype and the lung disease come apart. And the functional signature reported alongside it is increased T-circle formation, the excised telomere loops that accumulate when the helicase fails to dismantle T-loops properly - which places the lesion at RTEL1's specific biochemical job rather than at telomerase.

Show evidence (8 references)

CGGV:assertion_d4ffc091-9706-4722-97c8-dfdc6e3084a6-2025-12-16T170000.000Z SUPPORT Other

The identifier this row binds, ClinGen's Definitive classification, and the mode of inheritance recorded as SD - semidominant - which is the fact the lump/split call turns on.

CGGV:assertion_d4ffc091-9706-4722-97c8-dfdc6e3084a6-2025-12-16T170000.000Z SUPPORT Other

"Therefore, the following disease entities have been lumped into one disease entity, autosomal dominant dyskeratosis congenita 4/ autosomal recessive dyskeratosis congenita 5 (OMIM:615190) and telomere related pulmonary fibrosis and/or bone marrow failure syndrome 3 (OMIM:616373)."

States in one sentence that RTEL1 causes both an autosomal dominant and an autosomal recessive entity alongside this one, which is why the numbered designation is a separate row here, and records ClinGen's wider entity boundary.

CGGV:assertion_d4ffc091-9706-4722-97c8-dfdc6e3084a6-2025-12-16T170000.000Z SUPPORT Other

"For cases with a later onset, respiratorypulmonary features like pulmonary fibrosis, interstitial pneumonia and dyspnea have been observed both as part of a syndromic presentation or isolated"

The clinical separation between this row and the childhood RTEL1 presentations. Quoted as it stands, including ClinGen's own run-together "respiratorypulmonary".

+ 5 more references

CST complex CTC1

CTC1 hgnc:26169 Autosomal recessive inheritance

Autosomal recessive DC caused by variants in CTC1, a component of the CTC1-STN1-TEN1 (CST) complex that supports telomere C-strand replication and interacts with DNA polymerase alpha-primase. CTC1 disease overlaps with Coats plus syndrome.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."

GeneReviews lists CTC1 as autosomal recessive DC/TBD.

Replication protein A1 (RPA1)

RPA1 hgnc:10289 Autosomal dominant inheritance

Autosomal dominant DC caused by variants in RPA1, a single-stranded DNA-binding protein involved in telomere replication.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."

GeneReviews lists RPA1 as autosomal dominant DC/TBD.

Shelterin ACD (TPP1)

ACD hgnc:25070 Autosomal dominant inheritance Autosomal recessive inheritance

DC caused by variants in ACD encoding the shelterin protein TPP1, which recruits and stimulates telomerase. ACD disease can be autosomal dominant or recessive. The dominant, OMIM-numbered designation for this gene is carried separately as the DKCA6 subtype below.

DKCA6

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."

GeneReviews lists ACD as dominant or recessive DC/TBD.

Dyskeratosis congenita, autosomal dominant 6 (ACD/TPP1 TEL patch) MONDO:0014690

ACD hgnc:25070 Autosomal dominant inheritance

The numbered, autosomal dominant designation for ACD/TPP1 telomere biology disease (OMIM 616553). It sits inside the gene-level ACD subtype above, which spans both dominant and recessive ACD disease; DKCA6 names the dominant half. The defining report is a family in which a single-amino-acid deletion in the TPP1 TEL patch, p.Lys170del, segregates with aplastic anaemia and related haematopoietic disease, and in which every carrier, but no wild-type relative, has short telomeres. The molecular lesion is specifically a telomerase-recruitment defect rather than a loss of telomere binding: expressed in 293T cells the mutant protein still reaches telomeres but no longer brings telomerase with it. Presentation in that family was led by bone marrow failure rather than by the classic mucocutaneous triad; how far that generalises is not established, since the dominant ACD allelic series is still small.

Show evidence (4 references)

PMID:25205116 SUPPORT Human Clinical

"Here, we identify a family with aplastic anemia and other related hematopoietic disorders in which a 1-amino-acid deletion in the TEL patch of TPP1 (ΔK170) segregates with disease."

Defines the subtype: a heterozygous TPP1 TEL-patch deletion segregating with bone marrow failure in one family.

PMID:25205116 SUPPORT Human Clinical

"All family members carrying this mutation, but not those with wild-type TPP1, have short telomeres."

Places the family inside the telomere biology disorder spectrum by tracking short telomeres with carrier status.

PMID:25205116 SUPPORT In Vitro

"When introduced into 293T cells, TPP1 with the ΔK170 mutation is able to localize to telomeres but fails to recruit telomerase to telomeres, supporting a causal relationship between this TPP1 mutation and bone marrow disorders."

Cell-based support for the specific mechanism stated in the description - telomerase recruitment fails while telomere localisation is preserved.

+ 1 more reference

H/ACA snoRNP NHP2

NHP2 hgnc:14377 Autosomal recessive inheritance

Autosomal recessive DC caused by variants in NHP2, an H/ACA ribonucleoprotein component required for telomerase RNA stability.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."

GeneReviews lists NHP2 as autosomal recessive DC/TBD.

H/ACA snoRNP NOP10

NOP10 hgnc:14378 Autosomal recessive inheritance

Autosomal recessive DC caused by variants in NOP10, an H/ACA ribonucleoprotein component required for telomerase RNA stability.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."

GeneReviews lists NOP10 as autosomal recessive DC/TBD.

Poly(A)-specific ribonuclease (PARN)

PARN hgnc:8609 Autosomal dominant inheritance Autosomal recessive inheritance

DC caused by variants in PARN, a deadenylase required for maturation of the telomerase RNA component (TERC). PARN disease can be autosomal dominant or recessive and is associated with pulmonary fibrosis.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."

GeneReviews lists PARN as dominant or recessive DC/TBD.

Dyskeratosis congenita, autosomal recessive 3 (DKCB3; WRAP53/TCAB1) MONDO:0013520

WRAP53 hgnc:25522 Autosomal recessive inheritance

Autosomal recessive DC caused by biallelic variants in WRAP53 (TCAB1), the telomerase holoenzyme protein that traffics telomerase to Cajal bodies for recruitment to telomeres. This is the numbered designation DKCB3 (OMIM 613988). The defining report identified compound heterozygous TCAB1 missense variants in DC patients and showed that they disrupt telomerase localization to Cajal bodies, misdirecting telomerase RNA to nucleoli so that telomerase never reaches the telomere to elongate it. A later consanguineous Han Chinese family homozygous for p.Arg298Trp extends the allelic spectrum beyond compound heterozygosity and supports the recessive mode: the three heterozygous relatives had no mucocutaneous symptoms and normal blood counts, while the proband's lymphocyte telomere length fell below the first percentile for age. Those relatives were not examined by marrow biopsy or pulmonary function testing, so their carrier status is unaffected on clinical grounds rather than exhaustively.

Show evidence (5 references)

PMID:20301779 SUPPORT Human Clinical

"Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."

GeneReviews lists WRAP53 as autosomal recessive DC/TBD.

PMID:21205863 SUPPORT DIRECT Human Clinical

"We identify DC patients with missense mutations in TCAB1, a telomerase holoenzyme protein that facilitates trafficking of telomerase to Cajal bodies"

The report that established WRAP53/TCAB1 as a dyskeratosis congenita gene, and the basis of the DKCB3 designation.

PMID:21205863 SUPPORT DIRECT In Vitro

"Compound heterozygous mutations in TCAB1 disrupt telomerase localization to Cajal bodies, resulting in misdirection of telomerase RNA to nucleoli, which prevents telomerase from elongating telomeres"

Gives the subtype-specific lesion - telomerase is made but never delivered to the telomere - which is what places DKCB3 on this entry's shared telomere-maintenance pathway. Graded IN_VITRO because the localization result is a cell-based experiment, not a clinical observation.

+ 2 more references

Shelterin POT1

POT1 hgnc:17284 Autosomal recessive inheritance

Autosomal recessive DC caused by variants in POT1, a shelterin component that binds telomeric single-stranded DNA. Novel POT1 variants expanding the DC allelic series reduce binding to telomeric ssDNA.

Show evidence (1 reference)

PMID:39198715 SUPPORT Human Clinical

"we have also identified several novel variants in POT1 and ZCCHC8 in multiple cases from different families expanding the allelic series of DC and DCL phenotypes."

Novel POT1 variants expand the DC allelic series.

POT1-related pulmonary fibrosis and/or bone marrow failure syndrome, telomere-related, 8 MONDO:0957263

POT1 hgnc:17284 Autosomal dominant inheritance

The adult, pulmonary-fibrosis-predominant POT1 presentation, and the eighth locus of the numbered telomere-related pulmonary fibrosis / bone marrow failure series. It is defined by a Dutch family carrying the heterozygous POT1 p.(L259S) allele in which idiopathic pulmonary fibrosis segregates dominantly with short leukocyte telomeres and genetic anticipation. This is the same shelterin gene as the recessive POT1 subtype above but a different clinical entity: dominant rather than recessive, adult rather than childhood, and led by lung disease rather than by the mucocutaneous triad. Mechanistically L259S is not a simple null - the mutant protein fails to bind the telomeric overhang, to accumulate in the nucleus, to regulate telomerase negatively and to support lagging-strand maintenance, and patient cells show telomere loss, telomere-induced DNA damage and premature senescence with G1 arrest. The evidence base is one family plus functional characterisation, so the phenotypic boundaries of this subtype remain provisional.

Show evidence (3 references)

PMID:35420632 SUPPORT Human Clinical

"Exonic sequencing identified a family with idiopathic pulmonary fibrosis (IPF) containing a previously unreported heterozygous mutation in POT1 p.(L259S)."

Defines the subtype: a heterozygous POT1 allele found in a family with idiopathic pulmonary fibrosis.

PMID:35420632 SUPPORT Human Clinical

"In this study, we show that a family carrying a POT1 mutation has typical characteristics of telomere syndromes, including (a) mutation-carrying family members have relatively short telomeres, (b) multiple phenotypes of short telomere syndromes are present in the family, and (c) the family shows..."

Places the family inside the telomere biology disorder spectrum on short telomeres, multi-organ short-telomere phenotypes and anticipation, which is what makes this a subtype of this entry rather than sporadic IPF.

PMID:35420632 SUPPORT In Vitro

"We found that POT1(L259S) is defective in binding the telomeric overhang, nuclear accumulation, negative regulation of telomerase, and lagging strand maintenance."

The molecular lesion behind this subtype, characterised biochemically.

Nuclear assembly factor 1 (NAF1)

NAF1 hgnc:25126 Autosomal dominant inheritance

Autosomal dominant DC/TBD caused by variants in NAF1, an H/ACA ribonucleoprotein assembly factor required for biogenesis and stability of the telomerase RNA component.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."

GeneReviews lists NAF1 as autosomal dominant DC/TBD.

CST complex STN1

STN1 hgnc:26200 Autosomal recessive inheritance

Autosomal recessive DC/TBD caused by variants in STN1, a component of the CST (CTC1-STN1-TEN1) complex that supports telomere replication and C-strand fill-in.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."

GeneReviews lists STN1 as autosomal recessive DC/TBD.

ZCCHC8 (nuclear exosome targeting complex)

ZCCHC8 hgnc:25265 Autosomal dominant inheritance

Autosomal dominant DC/TBD caused by variants in ZCCHC8, a component of the nuclear exosome targeting (NEXT) complex involved in processing/quality control of the telomerase RNA component.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."

GeneReviews lists ZCCHC8 as autosomal dominant DC/TBD.

Dyskeratosis congenita, digenic (TYMS-ENOSF1)

TYMS hgnc:12441 ENOSF1 hgnc:30365 Digenic inheritance

Dyskeratosis congenita in which affected individuals inherit a germline TYMS coding variant from one parent and a haplotype with rare variants in the TYMS antisense regulator ENOSF1 from the other. Neither parent is affected, so transmission is digenic rather than autosomal recessive at a single locus despite appearing recessive in the pedigree. The mechanism is nucleotide metabolic rather than telomerase or shelterin: TYMS is silenced post-transcriptionally by elevated ENOSF1, deoxyribonucleotide triphosphate pools are altered, and telomere maintenance becomes abnormal downstream of that. Affected cells are hypersensitive to the TYMS-specific inhibitor 5-fluorouracil. This row carries the genes and the mode of inheritance for the parent pathograph; the disease itself is curated as its own entry, Dyskeratosis_Congenita_Digenic, which is bound to MONDO:0031057. No subtype_term is bound here so that the same MONDO class is not bound twice.

Show evidence (2 references)

PMID:35931051 SUPPORT Human Clinical

"In a cohort of eight independent DC-affected families, we have identified a remarkable series of heterozygous germline variants in the gene encoding thymidylate synthase (TYMS)."

Establishes germline TYMS variants across eight DC families as the first locus of this subtype.

PMID:35931051 SUPPORT Human Clinical

"Targeted genomic sequencing identified a specific haplotype and rare variants in the naturally occurring TYMS antisense regulator ENOSF1 (enolase super family 1) inherited from the other parent."

Establishes ENOSF1 as the second, trans-inherited locus that makes this subtype digenic.

Apollo/SNM1B exonuclease deficiency (DCLRE1B; OMIM DKCB8) MONDO:0859319

DCLRE1B hgnc:17641 Autosomal recessive inheritance

Biallelic variants in DCLRE1B, encoding the 5'-to-3' DNA exonuclease Apollo/SNM1B, in individuals with a dyskeratosis congenita / Hoyeraal-Hreidarsson phenotype: early-onset hypocellular bone marrow failure, B and NK lymphopenia, developmental anomalies, microcephaly and intrauterine growth retardation. All reported patients carry a missense variant at the same catalytic-domain residue, L142. This row is a deliberate exception to the short-telomere criterion the rest of this entry is built on. Patient cells show telomere fragility and chromosome instability without global telomere shortening, and the founding report frames the entity as a genome-caretaker defect that reproduces the DC/HH clinical picture with normal telomere length. Telomere length testing therefore does not distinguish it. MONDO:0859319 is the class for this disease - OMIM:620133, gene MIM 609683 (DCLRE1B) - and MONDO's causal-gene axiom on it names DCLRE1B.

Show evidence (2 references)

PMID:35007328 SUPPORT Human Clinical

"We identified biallelic variants in the gene encoding the 5'-to-3' DNA exonuclease Apollo/SNM1B in 3 unrelated patients presenting with a DC/HH phenotype consisting of early-onset hypocellular bone marrow failure, B and NK lymphopenia, developmental anomalies, microcephaly, and/or intrauterine..."

Establishes biallelic DCLRE1B variants and the DC/Hoyeraal-Hreidarsson clinical picture recorded in this subtype's description.

PMID:35007328 SUPPORT In Vitro

"patients' cells showed signs of telomere fragility that were not associated with global reduction of telomere length"

Supports the exception recorded above: this subtype does not present with the short telomeres that define the rest of the entry.

Discussions and Knowledge Gaps

What accounts for the roughly 20% of clinically diagnosed dyskeratosis congenita / telomere biology disorder cases in which no pathogenic variant is identified in any of the 16 known DC/TBD genes?

KNOWLEDGE GAP OPEN gap_dc_unexplained_genetic_cause

Attached to

pathophysiology#Impaired Telomere Maintenance

GeneReviews reports that pathogenic variants in the 16 known DC/TBD genes are identified in approximately 80% of individuals meeting clinical diagnostic criteria, leaving roughly one in five clinically diagnosed patients genetically unexplained. These cases likely harbor variants in undiscovered genes, non-coding or structural variants in known loci, or somatic/mosaic events not captured by standard testing. Resolving this gap would extend the mechanistic chain (impaired telomere maintenance) to currently uncharacterized molecular causes and improve molecular diagnosis and counseling.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"in approximately 80% of individuals who meet"

GeneReviews reports a genetic diagnostic yield of approximately 80%, implying roughly 20% of clinically diagnosed DC/TBD remains genetically unexplained.

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Pathophysiology

Impaired Telomere Maintenance

The unifying upstream defect in DC is impaired telomere maintenance. Germline pathogenic variants in genes encoding telomerase (TERT catalytic subunit, TERC RNA template), the H/ACA snoRNP that stabilizes TERC (DKC1/dyskerin, NHP2, NOP10, NAF1), telomerase trafficking factors (WRAP53/TCAB1), the shelterin complex (TINF2, ACD/TPP1, POT1), the CST replication complex (CTC1, STN1, RPA1), and the RTEL1 helicase reduce the cell's ability to replenish telomeric repeats. Telomeres are nucleoprotein caps that prevent activation of the DNA damage response at chromosome ends.

Hematopoietic stem cell CL:0000037

DKC1 hgnc:2890 TERT hgnc:11730 TERC hgnc:11727 TINF2 hgnc:11824 RTEL1 hgnc:15888 CTC1 hgnc:26169 RPA1 hgnc:10289 ACD hgnc:25070 NHP2 hgnc:14377 NOP10 hgnc:14378 PARN hgnc:8609 WRAP53 hgnc:25522 POT1 hgnc:17284 POLA1 hgnc:9173 NAF1 hgnc:25126 STN1 hgnc:26200 ZCCHC8 hgnc:25265

Telomere maintenance GO:0000723 ↓ DECREASED Telomere maintenance via telomerase GO:0007004 ↓ DECREASED

Telomerase RNA binding GO:0070034

Telomerase holoenzyme complex GO:0005697

Animal models

Pot1a L261S knock-in mouse Mouse recapitulates The knock-in reproduces the upstream lesion of this entry: telomerase activity at telomeres falls in the presence of the mutant protein and telomeres shorten with successive generations.

Downstream

Critically Short Telomeres and Replicative Senescence

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres."

Establishes impaired telomere maintenance as the unifying cause of DC.

PMID:36151328 SUPPORT Human Clinical

"Mendelian defects in several of these factors can result in abnormally short or dysfunctional telomeres"

Mendelian defects in telomere factors produce short or dysfunctional telomeres.

Thymidylate Synthase Deficiency

In the digenic TYMS-ENOSF1 form the primary lesion is in nucleotide metabolism rather than in telomerase, shelterin or the CST complex. Post-transcriptional silencing of TYMS by elevated ENOSF1 leaves affected cells severely thymidylate-synthase deficient with altered deoxyribonucleotide triphosphate pools, and the resulting genotoxic stress and defective transcription make telomere maintenance abnormal as a downstream consequence.

Hematopoietic stem cell CL:0000037

TYMS hgnc:12441 ENOSF1 hgnc:30365

deoxyribonucleoside triphosphate metabolic process GO:0009200 ⚠ ABNORMAL

thymidylate synthase activity GO:0004799 ↓ DECREASED

Downstream

Impaired Telomere Maintenance The nucleotide-pool defect produces genotoxic stress and defective transcription, and telomere maintenance becomes abnormal as a consequence, which is how this metabolic lesion joins the shared telomere pathograph.

Show evidence (2 references)

PMID:35931051 SUPPORT In Vitro

"Lymphoblastoid cells from affected probands have severe TYMS deficiency, altered cellular deoxyribonucleotide triphosphate pools, and hypersensitivity to the TYMS-specific inhibitor 5-fluorouracil."

Supports both bindings on this node: reduced thymidylate synthase activity and abnormal deoxyribonucleoside triphosphate metabolism, measured in patient cells.

PMID:35931051 SUPPORT In Vitro

"Gene-rescue studies in cells from affected probands revealed that post-transcriptional epistatic silencing of TYMS is occurring via elevated ENOSF1."

Supports binding ENOSF1 to this node: it acts here by silencing TYMS rather than through a separate activity of its own.

Apollo Exonuclease Deficiency

In the DCLRE1B form the lesion is a hypomorphic 5'-to-3' DNA exonuclease. Patient cells show spontaneous chromosome instability and impaired DNA repair, complemented by correcting the gene, together with telomere fragility. Telomere length is not globally reduced, so this node does not feed the critically-short-telomere node that the telomerase, shelterin and CST lesions converge on; it reaches the same marrow failure by a genome-caretaker route instead.

Hematopoietic stem cell CL:0000037

DCLRE1B hgnc:17641

DNA repair GO:0006281 ↓ DECREASED

exonuclease activity GO:0004527 ↓ DECREASED

Downstream

Stem Cell Exhaustion in High-Turnover Tissues Chromosome instability and telomere fragility in the absence of functional Apollo produce early-onset hypocellular bone marrow failure, entering the shared pathograph at the stem cell compartment rather than through telomere shortening.

Show evidence (2 references)

PMID:35007328 SUPPORT In Vitro

"Apollo-deficient cells from patients exhibited spontaneous chromosome instability and impaired DNA repair that was complemented by CRISPR/Cas9-mediated gene correction."

Supports the reduced DNA repair bound on this node, and the gene correction rules out an unrelated cause in those patient lines.

PMID:35007328 SUPPORT In Vitro

"patients' cells showed signs of telomere fragility that were not associated with global reduction of telomere length"

Supports treating this as a telomere-fragility rather than a telomere-shortening node, which is why it bypasses the critically-short-telomere node.

Critically Short Telomeres and Replicative Senescence

Defective maintenance leads to progressive telomere attrition until telomeres become critically short or dysfunctional. Critically short telomeres are sensed as DNA damage, activating the p53/p21 DNA damage response and driving affected cells into replicative senescence or apoptosis, thereby limiting the replicative capacity of the tissue. Very short telomeres (often below the 1st percentile for age) are the diagnostic hallmark of DC.

Hematopoietic stem cell CL:0000037

Replicative senescence GO:0090399 ↑ INCREASED Apoptotic process GO:0006915 ↑ INCREASED p53-mediated DNA damage response GO:0030330 ↑ INCREASED

Downstream

Stem Cell Exhaustion in High-Turnover Tissues

Predisposition to myelodysplastic syndrome and acute myeloid leukemia Attached to the telomere/senescence node rather than to the downstream tissue-exhaustion node, because the route to malignancy is the genomic instability of critically short telomeres — chromosome-end fusion and breakage-fusion-bridge cycles — not the loss of stem-cell output itself. The two consequences of short telomeres diverge here: exhaustion produces the marrow failure, instability produces the clonal evolution.

Predisposition to squamous cell carcinoma The solid-tumour arm of the same genomic instability, arising characteristically in the head and neck and anogenital epithelia — the same high-turnover mucosal surfaces that carry the leukoplakia.

Cerebellar hypoplasia (Hoyeraal-Hreidarsson syndrome) A feature of the severe end of the spectrum rather than of classic DC: Hoyeraal-Hreidarsson syndrome is the variant defined by the shortest telomeres and earliest onset. Linked from this node rather than from tissue exhaustion because it is developmental — the cerebellum is not a high-turnover tissue — and the mechanism by which telomere shortening produces it is not established.

Exudative retinopathy (Revesz syndrome) The other severe-variant feature, defining Revesz syndrome, which dismech curates as its own entry. Same reasoning as the cerebellar feature: linked from the telomere node, with the mechanism unestablished.

Show evidence (2 references)

PMID:39371255 SUPPORT Human Clinical

"telomeres shorten continuously with each cell division until critically short telomeres prevent further proliferation whereby cells undergo terminal differentiation, senescence, or apoptosis."

Critically short telomeres halt proliferation and trigger senescence or apoptosis.

PMID:40215293 SUPPORT Model Organism

"Molecular analyses revealed a reduction of proliferating cells, increased apoptosis, and stem cell depletion with activation of the p53/p21 signaling pathway."

Ten1-knockout mouse model demonstrates p53/p21 activation, apoptosis, and stem cell depletion from telomere dysfunction.

Stem Cell Exhaustion in High-Turnover Tissues

Because telomere reserve restricts replicative capacity, tissues with high proliferative demand are preferentially affected. Premature replicative exhaustion of stem and progenitor cells in the bone marrow, immune system, skin and mucosa, liver, and lung produces the characteristic multisystem phenotype: bone marrow failure, mucocutaneous changes, and hepatic and pulmonary fibrosis. Genomic instability from dysfunctional telomeres also underlies the predisposition to myelodysplastic syndrome, leukemia, and squamous cell carcinoma.

Hematopoietic stem cell CL:0000037 Hematopoietic precursor cell CL:0008001 Pulmonary alveolar type 2 cell CL:0002063

Downstream

Bone marrow failure Exhaustion of hematopoietic stem and progenitor cells produces progressive bone marrow failure.

Pulmonary fibrosis Exhaustion of proliferative lung epithelial compartments contributes to telomere-biology-disorder pulmonary fibrosis.

Hepatic fibrosis and portal hypertension Telomere-driven cellular exhaustion in liver tissue predisposes to fibrotic/cirrhotic liver disease.

Nail dystrophy The nail bed is one of the high-turnover epithelia this node names, so nail dystrophy is the same exhaustion expressed in a different tissue as the marrow failure. It is the first component of the classic mucocutaneous triad.

Reticular skin pigmentation The second component of the triad. Skin is a continuously renewing epithelium, and the lacy pigmentation of the upper chest and neck is the cutaneous form of the same stem-cell exhaustion.

Oral leukoplakia The third component, in the oral mucosa — another high-turnover epithelium. It also matters beyond the triad, being the tissue from which the head-and-neck squamous carcinomas of this disease arise.

Immunodeficiency Lymphocytes are among the most proliferative cells in the body, so the telomere reserve is exhausted there as it is in the marrow. The immunodeficiency of DC is therefore part of the same high-turnover failure rather than a separate lesion.

Show evidence (1 reference)

PMID:39371255 SUPPORT Human Clinical

"altered telomere maintenance as observed in TBDs typically results in premature replicative cellular exhaustion in the respective organ systems eventually leading to life-threatening complications such as bone marrow failure (BMF), pulmonary fibrosis, and liver cirrhosis."

Premature replicative exhaustion in high-turnover organs causes bone marrow failure, pulmonary fibrosis, and liver cirrhosis.

⬡

Pathograph

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

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Phenotypes

Blood 3

Bone marrow failure Aplastic anemia HP:0001915

Course: PROGRESSIVE

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"People with DC/TBD are at increased risk for progressive bone marrow failure (BMF)"

Progressive bone marrow failure is a defining complication of DC.

PMID:37593443 SUPPORT Human Clinical

"Thirteen progressed to bone marrow failure at a median age of 8 years"

13/14 children progressed to bone marrow failure at median age 8 years.

Bone marrow hypocellularity HP:0005528

Show evidence (2 references)

PMID:39371255 SUPPORT Human Clinical

Replicative exhaustion of marrow precursors leads to bone marrow failure and hypocellularity.

ORPHA:1775 SUPPORT

"HP:0005528 | Bone marrow hypocellularity | Frequent (79-30%)"

Orphanet classifies bone marrow hypocellularity as frequent in dyskeratosis congenita.

Predisposition to myelodysplastic syndrome and acute myeloid leukemia Myelodysplasia HP:0002863

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia"

DC predisposes to myelodysplastic syndrome and acute myeloid leukemia.

Digestive 1

Hepatic fibrosis and portal hypertension Periportal fibrosis HP:0001405

Show evidence (2 references)

PMID:37184208 SUPPORT Human Clinical

"Liver abnormality (defined at baseline assessment by laboratory and/or radiological findings) was present in 72.4% of patients with predominantly cholestatic pattern of liver enzyme elevation."

Liver abnormality was present in 72.4% of DC/TBD patients with cholestatic pattern.

PMID:37184208 SUPPORT Human Clinical

"Clinically significant liver disease and portal hypertension developed in 17.2% of patients during the 6-year follow-up; this progression was mainly seen in patients with recessive or TINF2 -associated DC."

17.2% progressed to clinically significant liver disease and portal hypertension.

Eye 1

Exudative retinopathy (Revesz syndrome) Exudative vitreoretinopathy HP:0030490

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome"

Bilateral exudative retinopathy defines the Revesz severe DC variant.

Head and Neck 1

Oral leukoplakia VERY_FREQUENT HP:0002745

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia"

Oral leukoplakia is part of the diagnostic DC triad.

ORPHA:1775 SUPPORT

"HP:0002745 | Oral leukoplakia | Very frequent (99-80%)"

Orphanet classifies oral leukoplakia as very frequent in dyskeratosis congenita.

Immune 1

Immunodeficiency HP:0002721

Show evidence (1 reference)

PMID:39371255 SUPPORT Human Clinical

"a sufficient telomere reserve is particularly important in cells with high proliferative activity (e.g., hematopoiesis, immune cells, intestinal cells, liver, lung, and skin)."

Immune cells require telomere reserve; telomere depletion compromises immune function.

Integument 3

Nail dystrophy VERY_FREQUENT HP:0008404

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia"

Dysplastic nails are part of the diagnostic DC triad.

ORPHA:1775 SUPPORT

"HP:0008404 | Nail dystrophy | Very frequent (99-80%)"

Orphanet classifies nail dystrophy as very frequent in dyskeratosis congenita.

Reticular skin pigmentation Reticulated skin pigmentation HP:0007427

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia"

Lacy reticular pigmentation is part of the diagnostic DC triad.

ORPHA:1775 SUPPORT

"classic triad of nail dysplasia, skin pigmentary changes, and oral leukoplakia"

Orphanet's definition supports pigmentary skin change as part of the classic DC triad.

Predisposition to squamous cell carcinoma HP:0002860

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer)"

DC predisposes to squamous cell carcinoma of the head/neck or anogenital region.

Nervous System 1

Cerebellar hypoplasia (Hoyeraal-Hreidarsson syndrome) HP:0001321

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome)"

Cerebellar hypoplasia defines the Hoyeraal-Hreidarsson severe DC variant.

Respiratory 1

Pulmonary fibrosis HP:0002206

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis."

Pulmonary fibrosis is a recognized DC complication.

PMID:34479523 SUPPORT Human Clinical

"PF caused by DC should be kept in mind by clinicians in the differential diagnosis of patients with unexplained PF and should be excluded before diagnostic surgical lung biopsy is undertaken or empirical immunosuppression therapy is prescribed."

DC-associated pulmonary fibrosis should be excluded before lung biopsy or immunosuppression.

🧬

Genetic Associations

DKC1

Gene: DKC1 hgnc:2890 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

X-linked recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists DKC1 among the 16 genes causing DC/TBD.

TERT

Gene: TERT hgnc:11730 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists TERT among the 16 genes causing DC/TBD.

TERC

Gene: TERC hgnc:11727 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists TERC among the 16 genes causing DC/TBD.

TINF2

Gene: TINF2 hgnc:11824 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists TINF2 among the 16 genes causing DC/TBD.

RTEL1

Gene: RTEL1 hgnc:15888 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists RTEL1 among the 16 genes causing DC/TBD.

RTEL1-PFBMFT3

Gene: RTEL1 hgnc:15888 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance

Show evidence (2 references)

PMID:25607374 SUPPORT Human Clinical

"Evaluation of affected individuals in 163 additional kindreds revealed another eight families (4.7%) with heterozygous rare variants in RTEL1 that segregated with clinical FIP."

Source for the heterozygous, dominant transmission recorded on this record.

PMID:25607374 SUPPORT Human Clinical

"Probands and unaffected carriers of these rare variants had short telomeres (<10% for age) in peripheral blood mononuclear cells and increased T-circle formation, suggesting impaired RTEL1 function."

Source for the incomplete-penetrance statement in the notes: carriers share the telomere phenotype without the lung disease.

CTC1

Gene: CTC1 hgnc:26169 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists CTC1 among the 16 genes causing DC/TBD.

RPA1

Gene: RPA1 hgnc:10289 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists RPA1 among the 16 genes causing DC/TBD.

ACD

Gene: ACD hgnc:25070 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists ACD among the 16 genes causing DC/TBD.

ACD-DKCA6

Gene: ACD hgnc:25070 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance

Show evidence (3 references)

PMID:25205116 SUPPORT Human Clinical

"Here, we identify a family with aplastic anemia and other related hematopoietic disorders in which a 1-amino-acid deletion in the TEL patch of TPP1 (ΔK170) segregates with disease."

The allele and its segregation with disease, which is the basis for the germline origin and dominant mode recorded here.

PMID:25205116 SUPPORT Human Clinical

"All family members carrying this mutation, but not those with wild-type TPP1, have short telomeres."

Carrier status tracks with short telomeres, which is what makes the allele a telomere biology disorder allele rather than an incidental variant.

PMID:25205116 SUPPORT In Vitro

The cell-based experiment behind the recruitment-versus-binding distinction recorded in this record's notes; a 293T transfection, not a measurement in patient cells.

NHP2

Gene: NHP2 hgnc:14377 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists NHP2 among the 16 genes causing DC/TBD.

NOP10

Gene: NOP10 hgnc:14378 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists NOP10 among the 16 genes causing DC/TBD.

PARN

Gene: PARN hgnc:8609 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists PARN among the 16 genes causing DC/TBD.

WRAP53

Gene: WRAP53 hgnc:25522 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists WRAP53 among the 16 genes causing DC/TBD.

POT1

Gene: POT1 hgnc:17284 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:39198715 SUPPORT Human Clinical

"we have also identified several novel variants in POT1 and ZCCHC8 in multiple cases from different families expanding the allelic series of DC and DCL phenotypes."

Novel POT1 variants expand the DC allelic series.

POT1-PFBMFT8

Gene: POT1 hgnc:17284 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance

Show evidence (2 references)

PMID:35420632 SUPPORT Human Clinical

"Familial pulmonary fibrosis caused by a telomere-related gene mutation is usually an autosomal dominant disease."

Source for the dominant inheritance recorded on this record.

PMID:40954016 SUPPORT Model Organism

"Importantly, overexpression of telomerase in adult Pot1aL261S/L261S mice did not lead to telomere lengthening, suggesting that the POT1a-L261S mutant protein is blocking the activity of telomerase-elongating telomeres and acts as a dominant negative."

The experiment behind the DOMINANT_NEGATIVE functional impact recorded here; note it is a mouse result, not a measurement in patient cells.

POLA1

Gene: POLA1 hgnc:9173 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

X-linked recessive inheritance

Show evidence (2 references)

PMID:39198715 SUPPORT Human Clinical

"This led us to identify several novel pathogenic variants within known genetic loci and in the novel X-linked gene, POLA1."

POLA1 is a newly identified X-linked DC gene.

PMID:39198715 SUPPORT In Vitro

"Functional characterisation of novel POLA1 and POT1 variants, revealed pathogenic effects on protein-protein interactions with primase, CTC1-STN1-TEN1 (CST) and shelterin subunit complexes, that are critical for telomere maintenance."

Functional studies show POLA1 variants disrupt CST/shelterin/primase interactions required for telomere maintenance.

NAF1

Gene: NAF1 hgnc:25126 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists NAF1 among the 16 genes causing DC/TBD.

STN1

Gene: STN1 hgnc:26200 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists STN1 among the 16 genes causing DC/TBD.

ZCCHC8

Gene: ZCCHC8 hgnc:25265 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal dominant inheritance

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"

GeneReviews lists ZCCHC8 among the 16 genes causing DC/TBD.

PMID:39198715 SUPPORT Human Clinical

"we have also identified several novel variants in POT1 and ZCCHC8 in multiple cases from different families expanding the allelic series of DC and DCL phenotypes."

Novel ZCCHC8 variants expand the DC allelic series.

TYMS (Loss of function)

Gene: TYMS hgnc:12441 gene page

Show evidence (2 references)

PMID:35931051 SUPPORT Human Clinical

"In a cohort of eight independent DC-affected families, we have identified a remarkable series of heterozygous germline variants in the gene encoding thymidylate synthase (TYMS)."

Establishes germline TYMS variants in eight DC families.

PMID:35931051 SUPPORT In Vitro

"Lymphoblastoid cells from affected probands have severe TYMS deficiency, altered cellular deoxyribonucleotide triphosphate pools, and hypersensitivity to the TYMS-specific inhibitor 5-fluorouracil."

Confirms the loss-of-function consequence recorded on this record, measured in patient-derived cells.

ENOSF1 (Modifier)

Gene: ENOSF1 hgnc:30365 gene page relationship_type: COOPERATING

Show evidence (2 references)

PMID:35931051 SUPPORT Human Clinical

"Targeted genomic sequencing identified a specific haplotype and rare variants in the naturally occurring TYMS antisense regulator ENOSF1 (enolase super family 1) inherited from the other parent."

Establishes the ENOSF1 haplotype as the trans-inherited second locus.

PMID:35931051 SUPPORT In Vitro

"Gene-rescue studies in cells from affected probands revealed that post-transcriptional epistatic silencing of TYMS is occurring via elevated ENOSF1."

Supports the cooperating, epistatic mechanism recorded on this record rather than a direct loss of ENOSF1 function.

DCLRE1B (Loss of function)

Gene: DCLRE1B hgnc:17641

Show evidence (4 references)

PMID:35007328 SUPPORT Human Clinical

Establishes biallelic DCLRE1B variants as causal in three unrelated patients with a DC/Hoyeraal-Hreidarsson phenotype.

PMID:35007328 SUPPORT Human Clinical

"identify biallelic Apollo variants as a genetic cause of a hitherto unrecognized severe IBMFS that combines clinical hallmarks of DC/HH with normal telomere length"

Records the normal telomere length that makes this gene an exception to the entry's short-telomere diagnostic criterion.

PMID:35007328 SUPPORT Human Clinical

"All 3 patients carry a homozygous or compound heterozygous (in combination with a null allele) missense variant affecting the same residue L142 (L142F or L142S) located in the catalytic domain of Apollo."

Source for the recurrent catalytic-domain residue and the biallelic configuration recorded in the notes on this record.

+ 1 more reference

💊

Medical Actions

Hematopoietic stem cell transplantation

Action: hematopoietic stem cell transplantation Ontology label: Hematopoietic Cell Transplantation NCIT:C15431

Platform: Cell therapy

Hematopoietic cell transplantation is the only curative treatment for bone marrow failure and leukemia in DC, but historically has poor long-term outcome due to treatment toxicity. Radiation- and alkylator-reduced conditioning is favored, and related donors carrying the familial variant should be avoided.

Mechanism Target:

MODULATES Stem Cell Exhaustion in High-Turnover Tissues — HSCT replaces the dysfunctional short-telomere hematopoietic stem cell pool with donor-derived cells, rescuing hematopoiesis and reducing leukemia risk; it does not correct the underlying telomere maintenance defect in non-hematopoietic tissues.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Hematopoietic cell transplantation (HCT) is the only curative treatment for BMF and leukemia, but long-term outcome has historically been poor due to treatment toxicity"

HCT is the only curative treatment for DC marrow failure/leukemia but is toxicity-limited.

Androgen therapy (danazol)

Action: Pharmacotherapy NCIT:C15986

Agent: danazol CHEBI:4315 oxymetholone CHEBI:7864

Platform: Small molecule

Androgen therapy (e.g., danazol, oxymetholone) can improve blood counts and may be considered for bone marrow failure when a suitable transplant donor is not available. The combination of androgens with granulocyte colony-stimulating factor should be avoided because it has been associated with splenic rupture; monitoring of CBC, liver function, and liver ultrasound is recommended.

Mechanism Target:

MODULATES Impaired Telomere Maintenance — Androgens (danazol, oxymetholone) upregulate TERT expression, boosting telomerase activity in hematopoietic progenitors and partially reversing the telomere maintenance defect.

MODULATES Critically Short Telomeres and Replicative Senescence — By stimulating TERT, androgen therapy can slow the rate of telomere attrition in bone marrow progenitors, delaying progression to replicative senescence and improving blood counts.

Show evidence (2 references)

PMID:20301779 SUPPORT Human Clinical

"if a suitable donor is not available, androgen therapy may be considered for BMF."

Androgen therapy is an option for bone marrow failure when transplant is not available.

PMID:20301779 SUPPORT Human Clinical

"the combination of androgens and granulocyte colony-stimulating factor in treatment of BMF (has been associated with splenic rupture)"

GeneReviews Agents/Circumstances to Avoid - androgen plus G-CSF risks splenic rupture.

Lung transplantation

Action: organ transplantation Ontology label: Organ Transplantation NCIT:C15289

Platform: Surgery

Treatment of pulmonary fibrosis is primarily supportive, although lung transplantation may be considered for end-stage disease.

Mechanism Target:

MODULATES Stem Cell Exhaustion in High-Turnover Tissues — Lung transplantation replaces end-stage fibrotic lung tissue; it does not address the underlying telomere biology defect and DC patients face elevated post-transplant risks from impaired regenerative capacity in other high-turnover tissues.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Treatment of pulmonary fibrosis is primarily supportive, although lung transplantation may be considered."

Lung transplantation may be considered for DC-associated pulmonary fibrosis.

Cancer surveillance and supportive care

Action: supportive care Ontology label: Supportive Care NCIT:C15747

Surveillance is central to DC management, including annual CBC and bone marrow evaluation, monthly oral/head/neck self-examination with annual otolaryngology and dermatology screening, and annual pulmonary function tests. Of note, cancer therapy may pose an increased risk of prolonged cytopenias and pulmonary and hepatic toxicity, and non-irradiated/leukodepleted blood products should be used.

Show evidence (3 references)

PMID:20301779 SUPPORT Human Clinical

"cancer therapy may pose an increased risk for prolonged cytopenias as well as pulmonary and hepatic toxicity."

GeneReviews notes increased risk from cancer therapy, motivating surveillance and supportive care.

PMID:39048762 SUPPORT Human Clinical

"Studies described a 7-16-fold higher risk of secondary oral cancer (mainly squamous cell carcinoma) in allogeneic HCT (alloHCT) recipients, particularly in those who developed chronic graft versus host disease (cGVHD)."

The MASCC/ISOO statement quantifies the markedly elevated secondary oral cancer risk after allogeneic HCT, reinforcing oral-cancer surveillance in transplanted DC patients.

PMID:28533057 SUPPORT Other

"This companion article outlines consensus disease-specific long-term follow-up screening guidelines for patients with IMBFS."

Consensus late-effects screening guidelines for inherited bone marrow failure syndromes (which include dyskeratosis congenita) frame long-term post-transplant surveillance.

Genetic counseling

Action: Genetic Counseling NCIT:C15240

Genetic counseling addresses gene-specific mode of inheritance; once the familial variant is identified, prenatal and preimplantation genetic testing are possible. Family members should not donate blood if HCT is being considered, and potential related donors require telomere length and/or molecular testing.

Show evidence (1 reference)

PMID:20301779 SUPPORT Human Clinical

"Once the DC/TBD-related pathogenic variant(s) have been identified in an affected family member, prenatal and preimplantation genetic testing are possible."

Genetic counseling enables prenatal/preimplantation testing once the variant is known.

📈

Progression

Onset

Age: Childhood

Classic DC typically presents in childhood with mucocutaneous features and early bone marrow failure, whereas cryptic/adult-onset TBD may present in mid- or late adulthood with isolated pulmonary, hepatic, hematologic disease, or cancer.

Show evidence (2 references)

PMID:37593443 SUPPORT Human Clinical

"Fourteen patients were diagnosed with DC between the ages of 3 and 17 years (median, 8.5 years). They all had hematologic manifestations at diagnosis"

Childhood-diagnosed cohort with median diagnosis age 8.5 years and universal hematologic manifestations.

PMID:38066848 SUPPORT Human Clinical

"Adult-onset TBDs are often cryptic with isolated pulmonary, liver, or hematologic disease, or cancer, and may lack the classic disease-defining triad"

Adult-onset TBD presents cryptically and may lack the triad.

Bone marrow failure

The majority of children with classic DC progress to bone marrow failure, typically in the first or second decade of life.

Show evidence (1 reference)

PMID:37593443 SUPPORT Human Clinical

"Thirteen progressed to bone marrow failure at a median age of 8 years"

13/14 children progressed to bone marrow failure at median age 8 years.

📊

Prevalence

Global

Point Prevalence 0.5 per 100,000 (0.1–0.9) 1–9 per 1,000,000

DC is consistently described as an ultra-rare/rare inherited bone marrow failure syndrome. Orphanet reports a European point-prevalence class of 1-9 per 1,000,000.

Show evidence (2 references)

PMID:37593443 SUPPORT Human Clinical

"Dyskeratosis congenita (DC) is a multisystem and ultra-rare hereditary disease characterized by somatic involvement, bone marrow failure, and predisposition to cancer."

Characterizes DC as an ultra-rare hereditary multisystem disease.

ORPHA:1775 SUPPORT Other

"1-9 / 1 000 000 | Europe | Point prevalence | EXPERT"

Orphanet epidemiology table reports a European point-prevalence class of 1-9 per 1,000,000 for dyskeratosis congenita, supporting the numeric band.

📊

Related Datasets

RTEL1 mutation as a modifier of Dyskeratosis Congenita in a family with a Telomerase RNA (hTR) template mutation and variant telomeric repeats ega:EGAS50000001644

Vertebrate telomeres, the sequences protecting the end of linear chromosomes, are composed of conserved hexameric GGTTAG repeats. Here we present a C50>A telomerase RNA template mutation that results in the incorporation of the variant telomeric repeat GTTTAG in a family with dyskeratosis congenita primarily presenting as idiopathic pulmonary fibrosis. The mutant telomerase is characterized by decreased processivity in direct telomerase activity assays and in vivo based on data from Illumina next-generation whole genome sequencing and Oxford Nanopore Technologies long-read telomere sequencing.

human WGS

European Genome-phenome Archive study, matched because the disease is named in the study's own title ("Dyskeratosis Congenita"); description-level mentions were not accepted. EGA study_type: Whole Genome Sequencing. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.

🐁

Animal Models

Pot1a L261S knock-in mouse

A humanised knock-in of the murine residue homologous to the human POT1 L259S allele of the PFBMFT8 subtype. Homozygotes progressively shorten their telomeres across successive mouse generations and develop degenerative intestinal, testicular and lung pathology at old age, phenocopying the telomerase-knockout mouse.

Species

Mouse

Genotype

Pot1a L261S knock-in (homozygous and heterozygous), homologous to human POT1 p.L259S

Publication

PMID:40954016

Pathograph links

Impaired Telomere Maintenance recapitulates fidelity: moderate The knock-in reproduces the upstream lesion of this entry: telomerase activity at telomeres falls in the presence of the mutant protein and telomeres shorten with successive generations.

Limitations: The generational phenotype requires homozygosity, whereas human PFBMFT8 carriers are heterozygous; heterozygous mice show only a trend toward shorter telomeres. Mouse telomeres are far longer than human telomeres, which is why several generations of intercross are needed before a phenotype appears at all.

Readouts

Telomere length by telomeric Q-FISH across mouse generations

Direction: DECREASED

Interpretation: Direct measure of the telomere-maintenance deficit modelled by this link.

Show evidence (1 reference)

PMID:40954016 SUPPORT Model Organism

"We found that the homozygous Pot1a L261S mice show shorter telomeres and degenerative pathologies in the intestine, testes, and lungs at old ages, a phenotype that is aggravated with increasing mouse generations, in striking analogy to the telomerase-deficient mouse models."

Reports the shortened telomeres and their aggravation across generations that this readout records.

Show evidence (1 reference)

PMID:40954016 SUPPORT Model Organism

"We show that telomerase activity at telomeres is reduced in the presence of POT1a-L261S, which behaves as a dominant negative mutant, thus providing a potential mechanism by which Pot1a L261S knock-in mice phenocopy the short telomere phenotype of the telomerase knockout model."

Establishes the model as informative for the impaired telomere maintenance node.

{ }

Source YAML

click to show

name: Dyskeratosis Congenita
creation_date: "2026-06-05T12:00:00Z"
category: Mendelian
description: >-
  Dyskeratosis congenita (DC) is a rare inherited multisystem telomere biology
  disorder (TBD) caused by impaired telomere maintenance resulting in abnormally
  short or dysfunctional telomeres. Classic DC is defined by a mucocutaneous triad
  of dysplastic nails, lacy reticular skin pigmentation, and oral leukoplakia, and
  is complicated by progressive bone marrow failure, predisposition to
  myelodysplastic syndrome / acute myeloid leukemia and squamous cell carcinoma,
  and pulmonary and hepatic fibrosis. DC sits at the early-onset, classic end of
  the broader telomere biology disorder spectrum, with Hoyeraal-Hreidarsson
  syndrome (with cerebellar hypoplasia) and Revesz syndrome (with exudative
  retinopathy) representing severe variants. Pathogenic germline variants in at
  least 16 genes spanning the telomerase core (TERT, TERC), the H/ACA snoRNP
  (DKC1, NHP2, NOP10, NAF1), telomerase trafficking (WRAP53), the shelterin
  complex (TINF2, ACD, POT1), the CST replication complex (CTC1, STN1, RPA1), the
  RTEL1 helicase, and RNA-processing factors (PARN, ZCCHC8) cause DC, with
  X-linked, autosomal dominant, and autosomal recessive inheritance depending on
  the gene. Diagnosis relies on multicolor flow-FISH lymphocyte telomere length
  testing (very short telomeres, often below the 1st percentile for age) and
  germline genetic testing, which identifies a pathogenic variant in approximately
  80% of clinically diagnosed individuals. At the opposite, adult end of the same
  spectrum sit the numbered telomere-related pulmonary fibrosis / bone marrow
  failure entities, in which dominant variants in the same genes present decades
  later with lung disease rather than the mucocutaneous triad; the POT1 member of
  that series (PFBMFT8) is curated here as a subtype alongside the recessive POT1
  form.
disease_term:
  preferred_term: Dyskeratosis Congenita
  term:
    id: MONDO:0015780
    label: dyskeratosis congenita
parents:
- Bone Marrow Failure
- Inherited Bone Marrow Failure Syndrome
- Telomere Biology Disorder

classifications:
  iuis_category:
    classification_value: bone marrow failure
    notes: >-
      IUIS 2022 phenotypic classification of inborn errors of immunity (Tangye et
      al., PMID:35748970), Table 9 "Bone marrow failure". Dyskeratosis congenita is
      entered in that table as a block of fourteen gene rows sharing one Subcategory
      cell: DKCX1 (DKC1, XL), DKCA1 (TERC), DKCA2 (TERT), DKCA3 (TINF2), DKCA4
      (RTEL1), DKCA5 (TINF2), DKCA6 (ACD), DKCB1 (NOLA3), DKCB2 (NOLA2), DKCB3
      (WRAP53), DKCB4 (TERT), DKCB5 (RTEL1), DKCB6 (PARN) and DKCB7 (ACD). This
      entry is the union of that block and the assignment is made against it rather
      than against any one gene row. Two scope notes. First, the entry's
      has_subtypes list is broader than the table: CTC1, STN1, RPA1, POT1, POLA1,
      NAF1 and ZCCHC8 are curated here but the CTC1 and STN1 rows appear in Table 9
      under a separate "Coats plus syndrome" heading, and the remaining four
      telomere genes are not in Table 9 at all. Second, the DKCA5 row (TINF2, AD,
      OMIM 268130) is Revesz syndrome, which dismech curates as its own entry and
      which carries this same assignment there. Neither point changes the
      membership of dyskeratosis congenita proper.
    evidence:
    - reference: PMID:35748970
      reference_title: "Human Inborn Errors of Immunity: 2022 Update on the Classification from the International Union of Immunological Societies Expert Committee."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "reticulate skin pigmentation; microcephaly, neurodevelopmental delay Dyskeratosis Congenita"
      explanation: >-
        The close of the dyskeratosis congenita block in IUIS Table 9, read across
        the associated-features column into the Subcategory cell that names the
        disease. Graded OTHER because the cited source is an expert-committee
        nosology, not a primary study.
    - reference: PMID:35748970
      reference_title: "Human Inborn Errors of Immunity: 2022 Update on the Classification from the International Union of Immunological Societies Expert Committee."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "DKCX1 DKC1 XL 305000 DKCA1 TERC AD 127550 DKCA2 TERT AD 187270"
      explanation: >-
        The first three gene rows of the Table 9 dyskeratosis congenita block,
        showing the per-gene row structure (subtype key, gene, inheritance, OMIM)
        that this single entry spans. Graded OTHER for the same reason as the row
        above.

notes: >-
  Lump/split and mapping decisions recorded during a genetics pass over the
  gene-defined MONDO subtypes of this disease.

  Four of MONDO's gene-defined forms are curated as their own entries and are not
  given a subtype_term here, so that the same MONDO class is not bound twice:
  autosomal recessive 2 (MONDO:0013519, NHP2) in
  Dyskeratosis_Congenita_Autosomal_Recessive_2; autosomal recessive 6
  (MONDO:0014600, PARN) in Dyskeratosis_Congenita_Autosomal_Recessive_6;
  the digenic TYMS-ENOSF1 form (MONDO:0031057) in
  Dyskeratosis_Congenita_Digenic; and Revesz syndrome in
  Revesz_Syndrome, which carries the same TINF2 ClinGen assertion the DKCA3
  subtype cites here. Those diseases keep a gene-carrying row on this entry, as
  NHP2 already did, because the parent pathograph needs the gene.

  The digenic TYMS-ENOSF1 form and autosomal recessive 8 are distinct diseases
  with easily confused identifiers. MONDO:0031057 "dyskeratosis congenita,
  digenic" cross-references OMIM:620040 and MedGen C5774217, whose definition is
  the entity described by Tummala et al. 2022 and mentions the severe 5-FU
  reactions; its OMIM gene number is 188350 (TYMS). MONDO:0859319 "dyskeratosis
  congenita, autosomal recessive 8" cross-references OMIM:620133 and MedGen
  C5774257, whose definition is the Apollo/DCLRE1B entity described by Kermasson
  et al. 2022, in which telomeres are not shortened; its OMIM gene number is
  609683 (DCLRE1B). MONDO's causal-gene axioms agree on both classes. The DKCD row
  here is therefore a pointer to Dyskeratosis_Congenita_Digenic and carries no
  subtype_term, while the DCLRE1B row binds MONDO:0859319.

  Where a gene's subtype row spans both dominant and recessive transmission, the
  numbered MONDO class for one of those modes is recorded as a narrowMatch mapping
  rather than as the row's subtype_term: TERT (MONDO:0013521, DKCA2) and RTEL1
  (MONDO:0014076, DKCB5). Binding a dominant-only or recessive-only class as the
  identity of a row that covers both would state something the row does not mean.

  The NOP10 row is left without a MONDO binding for a different reason.
  MONDO:0009136 (dyskeratosis congenita, autosomal recessive 1, DKCB1) is the term
  the OMIM numbering assigns to NOP10 disease, but no ClinGen gene-validity
  assertion links NOP10 to it - the committed ClinGen snapshot curates NOP10 only
  against pulmonary fibrosis and/or bone marrow failure syndrome, telomere-related
  9 (MONDO:0957294), as Limited - and the GeneReviews chapter cited throughout this
  entry names the gene without the numbered designation. The binding is left for a
  curator with a citable source for the equivalence.

  One further MONDO observation, recorded for a maintainer rather than acted on.
  MONDO carries its DKC1 causal gene edge on MONDO:0100152 "DKC1-related
  disorder", a class whose only cross-reference is GARD:0026065, while the
  OMIM-anchored MONDO:0010584 "dyskeratosis congenita, X-linked" (OMIM:305000)
  carries no gene edge; ClinGen has curated DKC1 against both. MONDO:0010584 also
  carries "Hoyeraal Hreidarsson syndrome" as a synonym even though MONDO:0018045
  exists as a separate Hoyeraal-Hreidarsson class; the Revesz_Syndrome entry's
  notes already record the related problem that MONDO nests MONDO:0018045 under
  the X-linked term while Hoyeraal-Hreidarsson occurs with several other genes.
  The DCLRE1B row added by this pass is a further instance, since its founding
  report describes a DC/HH phenotype.

references:
- reference: PMID:20301779
  title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
  tags:
  - GeneReviews

inheritance:
- name: X-linked recessive inheritance
  inheritance_term:
    preferred_term: X-linked recessive inheritance
    term:
      id: HP:0001419
      label: X-linked recessive inheritance
  description: >-
    X-linked recessive inheritance applies to DKC1, the gene encoding dyskerin and
    historically the most common and most severe form of classic DC.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mode of inheritance of DC/TBD varies by gene: X-linked: DKC1."
    explanation: GeneReviews assigns X-linked inheritance specifically to DKC1.
- name: Autosomal dominant inheritance
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    Autosomal dominant inheritance applies to NAF1, RPA1, TERC, TINF2, and ZCCHC8,
    and is the most frequent mode in adult-onset (cryptic) TBD.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."
    explanation: GeneReviews lists the autosomal dominant DC/TBD genes.
  - reference: PMID:38066848
    reference_title: "Clinical manifestations of telomere biology disorders in adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "TBD genetic etiology includes all modes of inheritance, with autosomal dominant the most frequent in adult-onset disease."
    explanation: Autosomal dominant inheritance predominates in adult-onset TBD.
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    Autosomal recessive inheritance applies to CTC1, NHP2, NOP10, POT1, STN1, and
    WRAP53; ACD, PARN, RTEL1, and TERT can be inherited as either dominant or
    recessive.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."
    explanation: GeneReviews lists the autosomal recessive DC/TBD genes.
- name: Digenic inheritance
  inheritance_term:
    preferred_term: Digenic inheritance
    term:
      id: HP:0010984
      label: Digenic inheritance
  description: >-
    Digenic inheritance applies to the TYMS-ENOSF1 form, in which a germline TYMS
    coding variant inherited from one parent and a haplotype with rare variants
    in the TYMS antisense regulator ENOSF1 inherited from the other are both
    required. The pedigrees look recessive, but carriers of either variant alone
    are unaffected, so this is not autosomal recessive transmission at a single
    locus. The contributing genes are curated as the DKCD subtype and as the TYMS
    and ENOSF1 records in the genetic section.
  evidence:
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These cell and molecular abnormalities generated by the combination of
      germline digenic variants at the TYMS-ENOSF1 locus represent a unique
      pathogenetic pathway for DC causation in these affected individuals,
      whereas the parents who are carriers of either of these variants in a
      singular fashion remain unaffected.
    explanation: >-
      States the two-locus requirement and the unaffected single-variant carrier parents,
      which is what the HPO digenic inheritance term asserts.
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Although the inheritance appeared to be autosomal recessive, one parent in
      each family had a wild-type TYMS coding sequence.
    explanation: >-
      Records why the pedigrees read as recessive while the transmission is digenic.

prevalence:
- population: Global
  measure_type: POINT_PREVALENCE
  prevalence_class: BAND_1_9_PER_1000000
  rate_per_100000: 0.5
  rate_low: 0.1
  rate_high: 0.9
  notes: >-
    DC is consistently described as an ultra-rare/rare inherited bone marrow
    failure syndrome. Orphanet reports a European point-prevalence class of
    1-9 per 1,000,000.
  evidence:
  - reference: PMID:37593443
    reference_title: "Dyskeratosis congenita: natural history of the disease through the study of a cohort of patients diagnosed in childhood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dyskeratosis congenita (DC) is a multisystem and ultra-rare hereditary disease characterized by somatic involvement, bone marrow failure, and predisposition to cancer."
    explanation: Characterizes DC as an ultra-rare hereditary multisystem disease.
  - reference: ORPHA:1775
    reference_title: "Dyskeratosis congenita"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "1-9 / 1 000 000 | Europe | Point prevalence | EXPERT"
    explanation: Orphanet epidemiology table reports a European point-prevalence class of 1-9 per 1,000,000 for dyskeratosis congenita, supporting the numeric band.

progression:
- phase: Onset
  age_range: Childhood
  notes: >-
    Classic DC typically presents in childhood with mucocutaneous features and
    early bone marrow failure, whereas cryptic/adult-onset TBD may present in mid-
    or late adulthood with isolated pulmonary, hepatic, hematologic disease, or
    cancer.
  evidence:
  - reference: PMID:37593443
    reference_title: "Dyskeratosis congenita: natural history of the disease through the study of a cohort of patients diagnosed in childhood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Fourteen patients were diagnosed with DC between the ages of 3 and 17 years (median, 8.5 years). They all had hematologic manifestations at diagnosis"
    explanation: Childhood-diagnosed cohort with median diagnosis age 8.5 years and universal hematologic manifestations.
  - reference: PMID:38066848
    reference_title: "Clinical manifestations of telomere biology disorders in adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Adult-onset TBDs are often cryptic with isolated pulmonary, liver, or hematologic disease, or cancer, and may lack the classic disease-defining triad"
    explanation: Adult-onset TBD presents cryptically and may lack the triad.
- phase: Bone marrow failure
  notes: >-
    The majority of children with classic DC progress to bone marrow failure,
    typically in the first or second decade of life.
  evidence:
  - reference: PMID:37593443
    reference_title: "Dyskeratosis congenita: natural history of the disease through the study of a cohort of patients diagnosed in childhood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thirteen progressed to bone marrow failure at a median age of 8 years"
    explanation: 13/14 children progressed to bone marrow failure at median age 8 years.

has_subtypes:
- name: DKC1
  display_name: X-linked DC (DKC1, dyskerin)
  subtype_term:
    preferred_term: dyskeratosis congenita, X-linked
    term:
      id: MONDO:0010584
      label: dyskeratosis congenita, X-linked
  mappings:
    mondo_mappings:
    - term:
        id: MONDO:0100152
        label: DKC1-related disorder
      mapping_predicate: skos:broadMatch
      mapping_source: MONDO
      mapping_justification: >-
        MONDO:0100152 is a gene-scoped class covering DKC1-related disease in general,
        and is the class on which MONDO carries the DKC1 causal gene edge; the
        OMIM-anchored X-linked dyskeratosis congenita class bound above carries no such
        edge. It is recorded here as a broader cross-reference rather than as this
        subtype's identity.
  description: >-
    X-linked recessive DC caused by pathogenic variants in DKC1 encoding dyskerin,
    a core component of the H/ACA small nucleolar ribonucleoprotein required for
    pseudouridylation and for stability of the telomerase RNA component. DKC1
    disease is historically the most common and most severe classic DC form,
    including Hoyeraal-Hreidarsson syndrome.
  inheritance:
  - name: X-linked recessive inheritance
    inheritance_term:
      preferred_term: X-linked recessive inheritance
      term:
        id: HP:0001419
        label: X-linked recessive inheritance
  genes:
  - preferred_term: DKC1
    term:
      id: hgnc:2890
      label: DKC1
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mode of inheritance of DC/TBD varies by gene: X-linked: DKC1."
    explanation: GeneReviews assigns X-linked inheritance to DKC1.
  - reference: CGGV:assertion_bb90bea1-16e7-44da-8551-91fb5fd7088a-2025-09-22T170000.000Z
    reference_title: "DKC1 / dyskeratosis congenita, X-linked (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "DKC1 | HGNC:2890 | dyskeratosis congenita, X-linked | MONDO:0010584 | XL | Definitive | SOP11 | Hereditary Cancer Gene Curation Expert Panel"
    explanation: >-
      ClinGen curated DKC1 against the same X-linked dyskeratosis congenita class bound
      as this subtype's subtype_term, and classifies the relationship as Definitive.
- name: TERT
  display_name: Telomerase reverse transcriptase (TERT)
  mappings:
    mondo_mappings:
    - term:
        id: MONDO:0013521
        label: dyskeratosis congenita, autosomal dominant 2
      mapping_predicate: skos:narrowMatch
      mapping_source: MONDO
      mapping_justification: >-
        MONDO:0013521 is the autosomal dominant numbered form (DKCA2). This subtype row
        covers TERT disease under both dominant and recessive transmission, as
        GeneReviews records, so the numbered dominant class is narrower than the row and
        is recorded as a mapping rather than as its subtype_term.
  description: >-
    DC caused by variants in TERT, the catalytic protein subunit of telomerase.
    TERT-associated disease can be inherited as autosomal dominant or autosomal
    recessive and is a common cause of adult-onset/cryptic TBD with pulmonary or
    hepatic fibrosis.
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: TERT
    term:
      id: hgnc:11730
      label: TERT
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."
    explanation: GeneReviews lists TERT as dominant or recessive DC/TBD.
  - reference: CGGV:assertion_afb6ea76-e8ac-4a38-b42c-23fc18a9623b-2020-07-30T205843.081Z
    reference_title: "TERT / dyskeratosis congenita, autosomal dominant 2 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "TERT | HGNC:11730 | dyskeratosis congenita, autosomal dominant 2 | MONDO:0013521 | SD | Definitive | SOP7 | Hereditary Cancer Gene Curation Expert Panel"
    explanation: >-
      ClinGen curated TERT against the numbered dominant class mapped on this subtype and
      classifies the relationship as Definitive, under semidominant inheritance.
- name: TERC
  display_name: Telomerase RNA component (TERC)
  subtype_term:
    preferred_term: dyskeratosis congenita, autosomal dominant 1
    term:
      id: MONDO:0007485
      label: dyskeratosis congenita, autosomal dominant 1
  description: >-
    Autosomal dominant DC caused by variants in TERC, the RNA template subunit of
    telomerase. Frequently underlies later-onset disease with pulmonary fibrosis.
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  genes:
  - preferred_term: TERC
    term:
      id: hgnc:11727
      label: TERC
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."
    explanation: GeneReviews lists TERC as autosomal dominant DC/TBD.
  - reference: CGGV:assertion_cfdf86d0-9441-40bf-a1da-ab2c85f775cd-2024-11-25T170000.000Z
    reference_title: "TERC / dyskeratosis congenita, autosomal dominant 1 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "TERC | HGNC:11727 | dyskeratosis congenita, autosomal dominant 1 | MONDO:0007485 | AD | Definitive | SOP11 | Interstitial Lung Disease Gene Curation Expert Panel"
    explanation: >-
      ClinGen curated TERC against the numbered dominant class bound as this subtype's
      subtype_term, under autosomal dominant inheritance, and classifies the
      relationship as Definitive.
- name: TINF2
  display_name: Dyskeratosis congenita, autosomal dominant 3 (DKCA3; shelterin TINF2/TIN2)
  subtype_term:
    preferred_term: dyskeratosis congenita, autosomal dominant 3
    term:
      id: MONDO:0013522
      label: dyskeratosis congenita, autosomal dominant 3
  description: >-
    Autosomal dominant DC caused by variants in TINF2 encoding the shelterin
    component TIN2, and the numbered designation DKCA3 (OMIM 613990). TINF2
    disease is often severe and early-onset, and is enriched for severe variants
    including Revesz syndrome and progression to liver disease.

    TINF2 was found in 2008 by linkage in a family with autosomal dominant DC in
    which DKC1, TERC and TERT had already been excluded. The founding report
    identified K280E in a proband and five affected relatives, R282H in three
    further unrelated probands and R282S in a fifth, found none of them in
    unaffected relatives or in 298 controls, and so made TINF2 the first shelterin
    component linked to human disease. The narrow clustering of those alleles is
    the feature that carries through the rest of the TINF2 literature: the
    pathogenic variants sit in a short stretch of exon 6, and the severe
    phenotypes at the Revesz end of the spectrum come from the same window.
  review_notes: >-
    Lump/split: DKCA3 is bound to this gene-level row rather than curated as its
    own kb/disorders/ entry, and rather than as a separate numbered row beside
    the gene-level row.

    The criterion this entry already uses is whether the gene causes both
    dominant and recessive disease. DKCA6 (ACD) and PFBMFT8 (POT1) sit as
    separate numbered rows next to their gene-level rows precisely because those
    genes cause both, so the numbered designation names only half of what the
    gene-level row covers. TINF2 does not: ClinGen's Interstitial Lung Disease
    expert panel records the mode of inheritance for this gene-disease
    relationship as AD, and a targeted PubMed search - TINF2[tiab] AND ("autosomal
    recessive"[tiab] OR "compound heterozygous"[tiab] OR biallelic[tiab]) - returns
    ten records, all general telomere-biology reviews and case reports of other
    genes, with no recessive TINF2 entity among them. The gene-level
    row and DKCA3 therefore cover the same patients and a second row would be
    redundant, which is the same reasoning applied to DKCB3 on the WRAP53 row.

    ClinGen goes further than this entry does, and the difference is worth
    recording rather than silently adopting. Its curation lumps DKCA3, Revesz
    syndrome, Hoyeraal-Hreidarsson syndrome and pulmonary fibrosis into a single
    entity it calls TINF2-related short telomere syndrome, on the stated grounds
    that it found no difference in molecular mechanism or inheritance pattern
    between them. dismech keeps Revesz_Syndrome as a standalone entry against its
    own MONDO term, MONDO:0009990, because it has a distinct pathograph -
    bilateral exudative retinopathy and cerebellar hypoplasia from a nine-residue
    window of exon 6 - and that decision is not revisited here. This change binds
    one identifier and leaves the Revesz entry alone. A reader comparing the two
    resources should know that ClinGen would not draw the line where dismech
    does.
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  genes:
  - preferred_term: TINF2
    term:
      id: hgnc:11824
      label: TINF2
  evidence:
  - reference: PMID:37184208
    reference_title: "Progression of liver disease and portal hypertension in dyskeratosis congenita and related telomere biology disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "those with heterozygous TINF2 DC were significantly younger, predominantly male, and more likely to have DC-associated mucocutaneous triad features and severe bone marrow failure"
    explanation: TINF2 DC patients are younger with severe triad features and bone marrow failure.
  - reference: CGGV:assertion_b32866f2-6fa1-4a63-9624-3588d0811ea7-2025-02-20T170000.000Z
    reference_title: "TINF2 / dyskeratosis congenita, autosomal dominant 3 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      TINF2 | HGNC:11824 | dyskeratosis congenita, autosomal dominant 3 | MONDO:0013522 | AD |
      Definitive
    explanation: >-
      The identifier this row now binds, with ClinGen's classification of the
      gene-disease relationship as Definitive and - the part the lump/split call
      turns on - its mode of inheritance as AD.
  - reference: CGGV:assertion_b32866f2-6fa1-4a63-9624-3588d0811ea7-2025-02-20T170000.000Z
    reference_title: "TINF2 / dyskeratosis congenita, autosomal dominant 3 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      TINF2 was first reported in relation to dyskeratosis congenita, autosomal dominant 3
      (MONDO: 0013522) in 2008 (Savage et al., 2008 PMID: 18252230).
    explanation: >-
      Ties the MONDO identifier bound here to the founding TINF2 report, which is
      what makes DKCA3 the numbered designation for this row's disease rather than
      a neighbouring concept. quote_role REVIEW_SYNTHESIS because this sentence is
      ClinGen attributing someone else's finding, unlike the lumping decision two
      items down, which is ClinGen's own product.
  - reference: CGGV:assertion_b32866f2-6fa1-4a63-9624-3588d0811ea7-2025-02-20T170000.000Z
    reference_title: "TINF2 / dyskeratosis congenita, autosomal dominant 3 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      the four conditions– dyskeratosis congenita, autosomal dominant 3 (OMIM:613990), Revesz
      syndrome (OMIM:268130), Hoyeraal-Hreidarsson syndrome (ORPHA:3322), and pulmonary
      fibrosis (OMIM:178500), have been lumped into one disease entity– TINF2 -related short
      telomere syndrome.
    explanation: >-
      The source for the OMIM number recorded in this row's description, and for
      the statement in review_notes that ClinGen draws the entity boundary wider
      than dismech does.
  - reference: PMID:18252230
    reference_title: "TINF2, a component of the shelterin telomere protection complex, is mutated in dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a linkage scan was performed on a family with autosomal-dominant DC and no mutations in
      DKCI, TERC, or TERT
    explanation: >-
      The study design that found this gene, and the source for the dominant
      inheritance recorded on this row. Note the source's own typo, DKCI for
      DKC1, which is quoted as it stands.
  - reference: PMID:18252230
    reference_title: "TINF2, a component of the shelterin telomere protection complex, is mutated in dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      this led to the identification of TINF2 (14q11.2) mutations, K280E, in the proband and
      her five affected relatives and TINF2 R282H in three additional unrelated DC probands,
      including one with Revesz syndrome; a fifth DC proband had a R282S mutation.
    explanation: >-
      The variant series named in this row's description, which was otherwise
      carried only as prose. It also contains the founding paper's own link
      between this row and the standalone Revesz_Syndrome entry - one of the three
      R282H probands had Revesz syndrome - which is the observation review_notes
      discusses when it explains why dismech keeps the two apart where ClinGen
      does not.
  - reference: PMID:18252230
    reference_title: "TINF2, a component of the shelterin telomere protection complex, is mutated in dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      TINF2 mutations were not present in unaffected relatives, DC probands with mutations in
      DKC1, TERC, or TERT or 298 control subjects.
    explanation: >-
      The segregation and control data behind the gene-disease claim, including
      the 298-control denominator.
  - reference: PMID:18252230
    reference_title: "TINF2, a component of the shelterin telomere protection complex, is mutated in dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This represents the first shelterin complex mutation linked to human disease and confirms
      the role of very short telomeres as a diagnostic test for DC.
    explanation: >-
      Why this row sits inside the shelterin arm of this entry rather than with
      the telomerase-component subtypes, and the diagnostic claim the founding
      paper makes.
- name: RTEL1
  display_name: Regulator of telomere elongation helicase 1 (RTEL1)
  mappings:
    mondo_mappings:
    - term:
        id: MONDO:0014076
        label: dyskeratosis congenita, autosomal recessive 5
      mapping_predicate: skos:narrowMatch
      mapping_source: MONDO
      mapping_justification: >-
        MONDO:0014076 is the recessive numbered form (DKCB5). This row covers RTEL1
        disease under both dominant and recessive transmission, as GeneReviews records,
        so the recessive numbered class is narrower than the row. The dominant
        pulmonary-fibrosis end of RTEL1 disease is curated as the separate PFBMFT3
        subtype below.
  description: >-
    DC caused by variants in RTEL1, a DNA helicase that dismantles telomeric
    T-loops and supports telomere replication. RTEL1 disease can be autosomal
    dominant or recessive and includes Hoyeraal-Hreidarsson syndrome.
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: RTEL1
    term:
      id: hgnc:15888
      label: RTEL1
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."
    explanation: GeneReviews lists RTEL1 as dominant or recessive DC/TBD.
- name: PFBMFT3
  display_name: RTEL1-related pulmonary fibrosis and/or bone marrow failure, telomere-related, 3
  subtype_term:
    preferred_term: pulmonary fibrosis and/or bone marrow failure, Telomere-related, 3
    term:
      id: MONDO:0014613
      label: pulmonary fibrosis and/or bone marrow failure, Telomere-related, 3
  description: >-
    The adult, pulmonary-predominant RTEL1 presentation, and the third locus of
    the numbered telomere-related pulmonary fibrosis / bone marrow failure series
    (OMIM 616373). It is the dominant, later-onset half of a gene whose recessive
    half is Hoyeraal-Hreidarsson syndrome and severe childhood DC, and it is
    defined by two 2015 exome studies of familial pulmonary fibrosis.

    In the larger of the two, heterozygous rare RTEL1 variants segregated with
    familial interstitial pneumonia in nine of 188 kindreds - one of the original
    25 exome families and eight of a further 163 - a yield of about five percent.
    The second study found RTEL1 significantly enriched for new damaging and
    missense variants at conserved residues in familial pulmonary fibrosis cases
    against 2,816 controls, and put RTEL1 and PARN together at roughly seven
    percent of familial pulmonary fibrosis.

    Two features distinguish this subtype from the gene-level RTEL1 row above
    rather than merely renaming it. Penetrance is incomplete in a way the
    childhood presentations are not: unaffected carriers in these families have
    short telomeres too, so the short-telomere phenotype and the lung disease come
    apart. And the functional signature reported alongside it is increased T-circle
    formation, the excised telomere loops that accumulate when the helicase fails
    to dismantle T-loops properly - which places the lesion at RTEL1's specific
    biochemical job rather than at telomerase.
  review_notes: >-
    Lump/split: PFBMFT3 is curated as a separate numbered row beside the
    gene-level RTEL1 row, not folded into it and not given its own
    kb/disorders/ entry.

    The criterion this entry uses is whether the gene causes both dominant and
    recessive disease. Where it does, the numbered designation names only half of
    what the gene-level row covers, and a second row is warranted - that is why
    DKCA6 sits beside the ACD row and PFBMFT8 beside the POT1 row. Where it does
    not, as for WRAP53, the numbered designation and the gene-level row cover the
    same patients and folding is right. RTEL1 is unambiguously in the first group:
    the gene-level row already records both modes with GeneReviews evidence, and
    ClinGen classifies the RTEL1 relationship as semidominant, explicitly lumping
    an autosomal dominant DC4 / autosomal recessive DC5 entity with this one.
    PFBMFT3 names the dominant, adult, lung-led half.

    This is the same call made for PFBMFT8 (POT1) and the opposite of the call
    made for DKCA3 (TINF2), and the two differ only on this criterion: TINF2
    disease is dominant throughout, RTEL1 disease is not.

    ClinGen lumps more than dismech does here, as it does for TINF2, and that is
    recorded rather than adopted. Its curation merges OMIM 615190 and OMIM 616373
    into one semidominant telomere biology disorder on the grounds that it found
    no difference in molecular mechanism or phenotypic variability. dismech keeps
    the numbered rows because they are the identifiers MONDO carries and because
    the clinical pictures are worth distinguishing for a reader; the merge is
    noted so that a reader comparing the two resources is not surprised.

    The issue for this curation also asked whether Bone_Marrow_Failure_Syndrome_6
    is coverage. It is not: BMFS6 is an MDM4 entity, and the RTEL1 mention in that
    file is prose.
  genes:
  - preferred_term: RTEL1
    term:
      id: hgnc:15888
      label: RTEL1
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  evidence:
  - reference: CGGV:assertion_d4ffc091-9706-4722-97c8-dfdc6e3084a6-2025-12-16T170000.000Z
    reference_title: "RTEL1 / pulmonary fibrosis and/or bone marrow failure, Telomere-related, 3 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      RTEL1 | HGNC:15888 | pulmonary fibrosis and/or bone marrow failure, Telomere-related, 3
      | MONDO:0014613 | SD | Definitive
    explanation: >-
      The identifier this row binds, ClinGen's Definitive classification, and the
      mode of inheritance recorded as SD - semidominant - which is the fact the
      lump/split call turns on.
  - reference: CGGV:assertion_d4ffc091-9706-4722-97c8-dfdc6e3084a6-2025-12-16T170000.000Z
    reference_title: "RTEL1 / pulmonary fibrosis and/or bone marrow failure, Telomere-related, 3 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Therefore, the following disease entities have been lumped into one disease entity,
      autosomal dominant dyskeratosis congenita 4/ autosomal recessive dyskeratosis congenita
      5 (OMIM:615190) and telomere related pulmonary fibrosis and/or bone marrow failure
      syndrome 3 (OMIM:616373).
    explanation: >-
      States in one sentence that RTEL1 causes both an autosomal dominant and an
      autosomal recessive entity alongside this one, which is why the numbered
      designation is a separate row here, and records ClinGen's wider entity
      boundary.
  - reference: CGGV:assertion_d4ffc091-9706-4722-97c8-dfdc6e3084a6-2025-12-16T170000.000Z
    reference_title: "RTEL1 / pulmonary fibrosis and/or bone marrow failure, Telomere-related, 3 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      For cases with a later onset, respiratorypulmonary features like pulmonary fibrosis,
      interstitial pneumonia and dyspnea have been observed both as part of a syndromic
      presentation or isolated
    explanation: >-
      The clinical separation between this row and the childhood RTEL1
      presentations. Quoted as it stands, including ClinGen's own run-together
      "respiratorypulmonary".
  - reference: PMID:25607374
    reference_title: "Rare variants in RTEL1 are associated with familial interstitial pneumonia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Evaluation of affected individuals in 163 additional kindreds revealed another eight
      families (4.7%) with heterozygous rare variants in RTEL1 that segregated with clinical
      FIP.
    explanation: >-
      The defining case series for this subtype, with its denominator and the
      heterozygous, dominant form of the variants.
  - reference: PMID:25607374
    reference_title: "Rare variants in RTEL1 are associated with familial interstitial pneumonia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Probands and unaffected carriers of these rare variants had short telomeres (<10% for
      age) in peripheral blood mononuclear cells and increased T-circle formation, suggesting
      impaired RTEL1 function.
    explanation: >-
      Two things at once: the incomplete penetrance that distinguishes this
      subtype, since unaffected carriers share the short-telomere phenotype, and
      the T-circle signature that places the lesion at RTEL1's helicase function.
  - reference: PMID:25607374
    reference_title: "Rare variants in RTEL1 are associated with familial interstitial pneumonia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Rare loss-of-function variants in RTEL1 represent a newly defined genetic predisposition
      for FIP, supporting the importance of telomere-related pathways in pulmonary fibrosis.
    explanation: >-
      The authors' own statement of the entity, and of the loss-of-function
      mechanism ClinGen also records.
  - reference: PMID:25848748
    reference_title: "Exome sequencing links mutations in PARN and RTEL1 with familial pulmonary fibrosis and telomere shortening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      RTEL1, an established locus for dyskeratosis congenita, harbored significantly more new
      damaging and missense variants at conserved residues in cases than in controls
    explanation: >-
      The independent replication, in a case-control burden design rather than by
      segregation, and its framing of RTEL1 as a DC gene arriving in pulmonary
      fibrosis.
  - reference: PMID:25848748
    reference_title: "Exome sequencing links mutations in PARN and RTEL1 with familial pulmonary fibrosis and telomere shortening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Together, these genes explain ~7% of familial pulmonary fibrosis and strengthen the link
      between lung fibrosis and telomere dysfunction.
    explanation: >-
      The share of familial pulmonary fibrosis attributed to RTEL1 and PARN
      jointly. Quoted as a joint figure because the paper gives it as one; it is
      not an RTEL1-only rate.
- name: CTC1
  display_name: CST complex CTC1
  description: >-
    Autosomal recessive DC caused by variants in CTC1, a component of the
    CTC1-STN1-TEN1 (CST) complex that supports telomere C-strand replication and
    interacts with DNA polymerase alpha-primase. CTC1 disease overlaps with Coats
    plus syndrome.
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: CTC1
    term:
      id: hgnc:26169
      label: CTC1
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."
    explanation: GeneReviews lists CTC1 as autosomal recessive DC/TBD.
- name: RPA1
  display_name: Replication protein A1 (RPA1)
  description: >-
    Autosomal dominant DC caused by variants in RPA1, a single-stranded
    DNA-binding protein involved in telomere replication.
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  genes:
  - preferred_term: RPA1
    term:
      id: hgnc:10289
      label: RPA1
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."
    explanation: GeneReviews lists RPA1 as autosomal dominant DC/TBD.
- name: ACD
  display_name: Shelterin ACD (TPP1)
  description: >-
    DC caused by variants in ACD encoding the shelterin protein TPP1, which
    recruits and stimulates telomerase. ACD disease can be autosomal dominant or
    recessive. The dominant, OMIM-numbered designation for this gene is carried
    separately as the DKCA6 subtype below.
  children:
  - DKCA6
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: ACD
    term:
      id: hgnc:25070
      label: ACD
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."
    explanation: GeneReviews lists ACD as dominant or recessive DC/TBD.
- name: DKCA6
  display_name: Dyskeratosis congenita, autosomal dominant 6 (ACD/TPP1 TEL patch)
  subtype_term:
    preferred_term: dyskeratosis congenita, autosomal dominant 6
    term:
      id: MONDO:0014690
      label: dyskeratosis congenita, autosomal dominant 6
  description: >-
    The numbered, autosomal dominant designation for ACD/TPP1 telomere biology
    disease (OMIM 616553). It sits inside the gene-level ACD subtype above,
    which spans both dominant and recessive ACD disease; DKCA6 names the
    dominant half. The defining report is a family in which a single-amino-acid
    deletion in the TPP1 TEL patch, p.Lys170del, segregates with aplastic
    anaemia and related haematopoietic disease, and in which every carrier,
    but no wild-type relative, has short telomeres. The molecular lesion is
    specifically a telomerase-recruitment defect rather than a loss of
    telomere binding: expressed in 293T cells the mutant protein still reaches
    telomeres but no longer brings telomerase with it. Presentation in that
    family was led by bone marrow failure rather than by the classic
    mucocutaneous triad; how far that generalises is not established, since the
    dominant ACD allelic series is still small.
  review_notes: >-
    Scoped to the dominant designation deliberately. The curation stub for
    MONDO:0014690 listed "dyskeratosis congenita, autosomal recessive 7" among
    its synonyms, so the ontology term may be slightly broader than this
    AD-only row; MONDO's current exact synonyms for the term are all AD6
    spellings and its own definition names an autosomal dominant ACD mutation,
    so the row was kept dominant rather than widened. Recessive ACD disease
    stays on the gene-level ACD row above.
  genes:
  - preferred_term: ACD
    term:
      id: hgnc:25070
      label: ACD
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  evidence:
  - reference: PMID:25205116
    reference_title: "Inherited bone marrow failure associated with germline mutation of ACD, the gene encoding telomere protein TPP1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we identify a family with aplastic anemia and other related hematopoietic disorders in which a 1-amino-acid deletion in the TEL patch of TPP1 (ΔK170) segregates with disease.
    explanation: >-
      Defines the subtype: a heterozygous TPP1 TEL-patch deletion segregating
      with bone marrow failure in one family.
  - reference: PMID:25205116
    reference_title: "Inherited bone marrow failure associated with germline mutation of ACD, the gene encoding telomere protein TPP1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All family members carrying this mutation, but not those with wild-type TPP1, have short telomeres.
    explanation: >-
      Places the family inside the telomere biology disorder spectrum by
      tracking short telomeres with carrier status.
  - reference: PMID:25205116
    reference_title: "Inherited bone marrow failure associated with germline mutation of ACD, the gene encoding telomere protein TPP1."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      When introduced into 293T cells, TPP1 with the ΔK170 mutation is able to localize to telomeres but fails to recruit telomerase to telomeres, supporting a causal relationship between this TPP1 mutation and bone marrow disorders.
    explanation: >-
      Cell-based support for the specific mechanism stated in the description -
      telomerase recruitment fails while telomere localisation is preserved.
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."
    explanation: GeneReviews records dominant inheritance as one of the two ACD modes.
- name: NHP2
  display_name: H/ACA snoRNP NHP2
  description: >-
    Autosomal recessive DC caused by variants in NHP2, an H/ACA
    ribonucleoprotein component required for telomerase RNA stability.
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: NHP2
    term:
      id: hgnc:14377
      label: NHP2
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."
    explanation: GeneReviews lists NHP2 as autosomal recessive DC/TBD.
- name: NOP10
  display_name: H/ACA snoRNP NOP10
  description: >-
    Autosomal recessive DC caused by variants in NOP10, an H/ACA
    ribonucleoprotein component required for telomerase RNA stability.
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: NOP10
    term:
      id: hgnc:14378
      label: NOP10
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."
    explanation: GeneReviews lists NOP10 as autosomal recessive DC/TBD.
- name: PARN
  display_name: Poly(A)-specific ribonuclease (PARN)
  description: >-
    DC caused by variants in PARN, a deadenylase required for maturation of the
    telomerase RNA component (TERC). PARN disease can be autosomal dominant or
    recessive and is associated with pulmonary fibrosis.
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: PARN
    term:
      id: hgnc:8609
      label: PARN
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant or autosomal recessive: ACD, PARN, RTEL1, and TERT."
    explanation: GeneReviews lists PARN as dominant or recessive DC/TBD.
- name: WRAP53
  display_name: Dyskeratosis congenita, autosomal recessive 3 (DKCB3; WRAP53/TCAB1)
  subtype_term:
    preferred_term: dyskeratosis congenita, autosomal recessive 3
    term:
      id: MONDO:0013520
      label: dyskeratosis congenita, autosomal recessive 3
  description: >-
    Autosomal recessive DC caused by biallelic variants in WRAP53 (TCAB1), the
    telomerase holoenzyme protein that traffics telomerase to Cajal bodies for
    recruitment to telomeres. This is the numbered designation DKCB3 (OMIM
    613988). The defining report identified compound heterozygous TCAB1 missense
    variants in DC patients and showed that they disrupt telomerase localization
    to Cajal bodies, misdirecting telomerase RNA to nucleoli so that telomerase
    never reaches the telomere to elongate it. A later consanguineous Han
    Chinese family homozygous for p.Arg298Trp extends the allelic spectrum
    beyond compound heterozygosity and supports the recessive mode: the three
    heterozygous relatives had no mucocutaneous symptoms and normal blood
    counts, while the proband's lymphocyte telomere length fell below the first
    percentile for age. Those relatives were not examined by marrow biopsy or
    pulmonary function testing, so their carrier status is unaffected on
    clinical grounds rather than exhaustively.
  review_notes: >-
    Lump/split: DKCB3 is curated as this gene-level subtype row rather than as
    its own kb/disorders/ entry, and rather than as a separate numbered row
    alongside it. The lesion is a telomerase-delivery defect, so the mechanism
    runs through the same telomere-maintenance pathway as the rest of this
    entry - unlike Dyskeratosis_Congenita_Digenic, which is a
    standalone entry because its mechanism runs through nucleotide metabolism
    instead. And unlike DKCA6, which names only the dominant half of a gene
    that causes both dominant and recessive disease, WRAP53 DC is recessive
    throughout, so the gene-level row and the numbered designation cover the
    same set of patients and a second row would be redundant.
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: WRAP53
    term:
      id: hgnc:25522
      label: WRAP53
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."
    explanation: GeneReviews lists WRAP53 as autosomal recessive DC/TBD.
  - reference: PMID:21205863
    reference_title: "Disruption of telomerase trafficking by TCAB1 mutation causes dyskeratosis congenita."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identify DC patients with missense mutations in TCAB1, a telomerase holoenzyme protein that facilitates trafficking of telomerase to Cajal bodies"
    explanation: The report that established WRAP53/TCAB1 as a dyskeratosis congenita gene, and the basis of the DKCB3 designation.
  - reference: PMID:21205863
    reference_title: "Disruption of telomerase trafficking by TCAB1 mutation causes dyskeratosis congenita."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    snippet: "Compound heterozygous mutations in TCAB1 disrupt telomerase localization to Cajal bodies, resulting in misdirection of telomerase RNA to nucleoli, which prevents telomerase from elongating telomeres"
    explanation: >-
      Gives the subtype-specific lesion - telomerase is made but never delivered
      to the telomere - which is what places DKCB3 on this entry's shared
      telomere-maintenance pathway. Graded IN_VITRO because the localization
      result is a cell-based experiment, not a clinical observation.
  - reference: PMID:29514627
    reference_title: "A unique homozygous WRAP53 Arg298Trp mutation underlies dyskeratosis congenita in a Chinese Han family."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "implying that DC with the WRAP53 mutation has an autosomal recessive inheritance mode"
    explanation: Segregation in a consanguineous family, with three asymptomatic heterozygous relatives, supports the recessive mode recorded on this row.
  - reference: PMID:29514627
    reference_title: "A unique homozygous WRAP53 Arg298Trp mutation underlies dyskeratosis congenita in a Chinese Han family."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "The telomere length in the peripheral blood lymphocytes from the proband (IV-1) corresponded to less than the 1st percentile of age-matched controls"
    explanation: Confirms that the WRAP53 trafficking defect produces the short-telomere phenotype in a patient, not only in cell-based assays.
- name: POT1
  display_name: Shelterin POT1
  description: >-
    Autosomal recessive DC caused by variants in POT1, a shelterin component that
    binds telomeric single-stranded DNA. Novel POT1 variants expanding the DC
    allelic series reduce binding to telomeric ssDNA.
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: POT1
    term:
      id: hgnc:17284
      label: POT1
  evidence:
  - reference: PMID:39198715
    reference_title: "The evolving genetic landscape of telomere biology disorder dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we have also identified several novel variants in POT1 and ZCCHC8 in multiple cases from different families expanding the allelic series of DC and DCL phenotypes."
    explanation: Novel POT1 variants expand the DC allelic series.
- name: PFBMFT8
  display_name: POT1-related pulmonary fibrosis and/or bone marrow failure syndrome, telomere-related, 8
  subtype_term:
    preferred_term: pulmonary fibrosis and/or bone marrow failure syndrome, telomere-related, 8
    term:
      id: MONDO:0957263
      label: pulmonary fibrosis and/or bone marrow failure syndrome, telomere-related, 8
  description: >-
    The adult, pulmonary-fibrosis-predominant POT1 presentation, and the eighth
    locus of the numbered telomere-related pulmonary fibrosis / bone marrow
    failure series. It is defined by a Dutch family carrying the heterozygous
    POT1 p.(L259S) allele in which idiopathic pulmonary fibrosis segregates
    dominantly with short leukocyte telomeres and genetic anticipation. This is
    the same shelterin gene as the recessive POT1 subtype above but a different
    clinical entity: dominant rather than recessive, adult rather than
    childhood, and led by lung disease rather than by the mucocutaneous triad.
    Mechanistically L259S is not a simple null - the mutant protein fails to
    bind the telomeric overhang, to accumulate in the nucleus, to regulate
    telomerase negatively and to support lagging-strand maintenance, and patient
    cells show telomere loss, telomere-induced DNA damage and premature
    senescence with G1 arrest. The evidence base is one family plus functional
    characterisation, so the phenotypic boundaries of this subtype remain
    provisional.
  genes:
  - preferred_term: POT1
    term:
      id: hgnc:17284
      label: POT1
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  evidence:
  - reference: PMID:35420632
    reference_title: >-
      Telomere dysfunction implicates POT1 in patients with idiopathic pulmonary fibrosis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Exonic sequencing identified a family with idiopathic pulmonary fibrosis (IPF) containing a previously unreported heterozygous mutation in POT1 p.(L259S).
    explanation: >-
      Defines the subtype: a heterozygous POT1 allele found in a family with
      idiopathic pulmonary fibrosis.
  - reference: PMID:35420632
    reference_title: >-
      Telomere dysfunction implicates POT1 in patients with idiopathic pulmonary fibrosis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In this study, we show that a family carrying a POT1 mutation has typical characteristics of telomere syndromes, including (a) mutation-carrying family members have relatively short telomeres, (b) multiple phenotypes of short telomere syndromes are present in the family, and (c) the family shows genetic anticipation (earlier onset of disease in subsequent generations).
    explanation: >-
      Places the family inside the telomere biology disorder spectrum on short
      telomeres, multi-organ short-telomere phenotypes and anticipation, which
      is what makes this a subtype of this entry rather than sporadic IPF.
  - reference: PMID:35420632
    reference_title: >-
      Telomere dysfunction implicates POT1 in patients with idiopathic pulmonary fibrosis.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      We found that POT1(L259S) is defective in binding the telomeric overhang, nuclear accumulation, negative regulation of telomerase, and lagging strand maintenance.
    explanation: >-
      The molecular lesion behind this subtype, characterised biochemically.
- name: NAF1
  display_name: Nuclear assembly factor 1 (NAF1)
  description: >-
    Autosomal dominant DC/TBD caused by variants in NAF1, an H/ACA
    ribonucleoprotein assembly factor required for biogenesis and stability of the
    telomerase RNA component.
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  genes:
  - preferred_term: NAF1
    term:
      id: hgnc:25126
      label: NAF1
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."
    explanation: GeneReviews lists NAF1 as autosomal dominant DC/TBD.
- name: STN1
  display_name: CST complex STN1
  description: >-
    Autosomal recessive DC/TBD caused by variants in STN1, a component of the CST
    (CTC1-STN1-TEN1) complex that supports telomere replication and C-strand fill-in.
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: STN1
    term:
      id: hgnc:26200
      label: STN1
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive: CTC1, NHP2, NOP10, POT1, STN1, and WRAP53."
    explanation: GeneReviews lists STN1 as autosomal recessive DC/TBD.
- name: ZCCHC8
  display_name: ZCCHC8 (nuclear exosome targeting complex)
  description: >-
    Autosomal dominant DC/TBD caused by variants in ZCCHC8, a component of the
    nuclear exosome targeting (NEXT) complex involved in processing/quality control
    of the telomerase RNA component.
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  genes:
  - preferred_term: ZCCHC8
    term:
      id: hgnc:25265
      label: ZCCHC8
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant: NAF1, RPA1, TERC, TINF2, and ZCCHC8."
    explanation: GeneReviews lists ZCCHC8 as autosomal dominant DC/TBD.

- name: DKCD
  display_name: Dyskeratosis congenita, digenic (TYMS-ENOSF1)
  description: >-
    Dyskeratosis congenita in which affected individuals inherit a germline TYMS
    coding variant from one parent and a haplotype with rare variants in the
    TYMS antisense regulator ENOSF1 from the other. Neither parent is affected,
    so transmission is digenic rather than autosomal recessive at a single locus
    despite appearing recessive in the pedigree. The mechanism is nucleotide
    metabolic rather than telomerase or shelterin: TYMS is silenced
    post-transcriptionally by elevated ENOSF1, deoxyribonucleotide triphosphate
    pools are altered, and telomere maintenance becomes abnormal downstream of
    that. Affected cells are hypersensitive to the TYMS-specific inhibitor
    5-fluorouracil.

    This row carries the genes and the mode of inheritance for the parent
    pathograph; the disease itself is curated as its own entry,
    Dyskeratosis_Congenita_Digenic, which is bound to MONDO:0031057. No
    subtype_term is bound here so that the same MONDO class is not bound twice.
  curated_in: Dyskeratosis_Congenita_Digenic
  inheritance:
  - name: Digenic inheritance
    inheritance_term:
      preferred_term: Digenic inheritance
      term:
        id: HP:0010984
        label: Digenic inheritance
    description: >-
      Disease requires a TYMS variant from one parent together with the ENOSF1
      haplotype from the other; single carriers of either remain unaffected.
    evidence:
    - reference: PMID:35931051
      reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        These cell and molecular abnormalities generated by the combination of
        germline digenic variants at the TYMS-ENOSF1 locus represent a unique
        pathogenetic pathway for DC causation in these affected individuals,
        whereas the parents who are carriers of either of these variants in a
        singular fashion remain unaffected.
      explanation: >-
        States the digenic requirement and the unaffected single-variant carrier parents,
        which is what the HPO digenic inheritance term asserts.
  genes:
  - preferred_term: TYMS
    term:
      id: hgnc:12441
      label: TYMS
  - preferred_term: ENOSF1
    term:
      id: hgnc:30365
      label: ENOSF1
  evidence:
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In a cohort of eight independent DC-affected families, we have identified
      a remarkable series of heterozygous germline variants in the gene encoding
      thymidylate synthase (TYMS).
    explanation: >-
      Establishes germline TYMS variants across eight DC families as the first locus of
      this subtype.
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Targeted genomic sequencing identified a specific haplotype and rare
      variants in the naturally occurring TYMS antisense regulator ENOSF1
      (enolase super family 1) inherited from the other parent.
    explanation: >-
      Establishes ENOSF1 as the second, trans-inherited locus that makes this subtype
      digenic.
- name: DCLRE1B
  display_name: Apollo/SNM1B exonuclease deficiency (DCLRE1B; OMIM DKCB8)
  description: >-
    Biallelic variants in DCLRE1B, encoding the 5'-to-3' DNA exonuclease
    Apollo/SNM1B, in individuals with a dyskeratosis congenita /
    Hoyeraal-Hreidarsson phenotype: early-onset hypocellular bone marrow
    failure, B and NK lymphopenia, developmental anomalies, microcephaly and
    intrauterine growth retardation. All reported patients carry a missense
    variant at the same catalytic-domain residue, L142.

    This row is a deliberate exception to the short-telomere criterion the rest
    of this entry is built on. Patient cells show telomere fragility and
    chromosome instability without global telomere shortening, and the founding
    report frames the entity as a genome-caretaker defect that reproduces the
    DC/HH clinical picture with normal telomere length. Telomere length testing
    therefore does not distinguish it.

    MONDO:0859319 is the class for this disease - OMIM:620133, gene MIM 609683
    (DCLRE1B) - and MONDO's causal-gene axiom on it names DCLRE1B.
  subtype_term:
    preferred_term: dyskeratosis congenita, autosomal recessive 8
    term:
      id: MONDO:0859319
      label: dyskeratosis congenita, autosomal recessive 8
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  genes:
  - preferred_term: DCLRE1B
    term:
      id: hgnc:17641
      label: DCLRE1B
  evidence:
  - reference: PMID:35007328
    reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We identified biallelic variants in the gene encoding the 5'-to-3' DNA
      exonuclease Apollo/SNM1B in 3 unrelated patients presenting with a DC/HH
      phenotype consisting of early-onset hypocellular bone marrow failure, B
      and NK lymphopenia, developmental anomalies, microcephaly, and/or
      intrauterine growth retardation.
    explanation: >-
      Establishes biallelic DCLRE1B variants and the DC/Hoyeraal-Hreidarsson clinical
      picture recorded in this subtype's description.
  - reference: PMID:35007328
    reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      patients' cells showed signs of telomere fragility that were not
      associated with global reduction of telomere length
    explanation: >-
      Supports the exception recorded above: this subtype does not present with the short
      telomeres that define the rest of the entry.
pathophysiology:
- name: Impaired Telomere Maintenance
  description: >-
    The unifying upstream defect in DC is impaired telomere maintenance. Germline
    pathogenic variants in genes encoding telomerase (TERT catalytic subunit, TERC
    RNA template), the H/ACA snoRNP that stabilizes TERC (DKC1/dyskerin, NHP2,
    NOP10, NAF1), telomerase trafficking factors (WRAP53/TCAB1), the shelterin
    complex (TINF2, ACD/TPP1, POT1), the CST replication complex (CTC1, STN1, RPA1),
    and the RTEL1 helicase reduce the cell's ability to replenish telomeric repeats.
    Telomeres are nucleoprotein caps that prevent activation of the DNA damage
    response at chromosome ends.
  cell_types:
  - preferred_term: Hematopoietic stem cell
    term:
      id: CL:0000037
      label: hematopoietic stem cell
  biological_processes:
  - preferred_term: Telomere maintenance
    term:
      id: GO:0000723
      label: telomere maintenance
    modifier: DECREASED
  - preferred_term: Telomere maintenance via telomerase
    term:
      id: GO:0007004
      label: telomere maintenance via telomerase
    modifier: DECREASED
  cellular_components:
  - preferred_term: Telomerase holoenzyme complex
    term:
      id: GO:0005697
      label: telomerase holoenzyme complex
  molecular_functions:
  - preferred_term: Telomerase RNA binding
    term:
      id: GO:0070034
      label: telomerase RNA binding
  genes:
  - preferred_term: DKC1
    term:
      id: hgnc:2890
      label: DKC1
  - preferred_term: TERT
    term:
      id: hgnc:11730
      label: TERT
  - preferred_term: TERC
    term:
      id: hgnc:11727
      label: TERC
  - preferred_term: TINF2
    term:
      id: hgnc:11824
      label: TINF2
  - preferred_term: RTEL1
    term:
      id: hgnc:15888
      label: RTEL1
  - preferred_term: CTC1
    term:
      id: hgnc:26169
      label: CTC1
  - preferred_term: RPA1
    term:
      id: hgnc:10289
      label: RPA1
  - preferred_term: ACD
    term:
      id: hgnc:25070
      label: ACD
  - preferred_term: NHP2
    term:
      id: hgnc:14377
      label: NHP2
  - preferred_term: NOP10
    term:
      id: hgnc:14378
      label: NOP10
  - preferred_term: PARN
    term:
      id: hgnc:8609
      label: PARN
  - preferred_term: WRAP53
    term:
      id: hgnc:25522
      label: WRAP53
  - preferred_term: POT1
    term:
      id: hgnc:17284
      label: POT1
  - preferred_term: POLA1
    term:
      id: hgnc:9173
      label: POLA1
  - preferred_term: NAF1
    term:
      id: hgnc:25126
      label: NAF1
  - preferred_term: STN1
    term:
      id: hgnc:26200
      label: STN1
  - preferred_term: ZCCHC8
    term:
      id: hgnc:25265
      label: ZCCHC8
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres."
    explanation: Establishes impaired telomere maintenance as the unifying cause of DC.
  - reference: PMID:36151328
    reference_title: "Genetics of human telomere biology disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mendelian defects in several of these factors can result in abnormally short or dysfunctional telomeres"
    explanation: Mendelian defects in telomere factors produce short or dysfunctional telomeres.
  downstream:
  - target: Critically Short Telomeres and Replicative Senescence
- name: Thymidylate Synthase Deficiency
  description: >-
    In the digenic TYMS-ENOSF1 form the primary lesion is in nucleotide
    metabolism rather than in telomerase, shelterin or the CST complex.
    Post-transcriptional silencing of TYMS by elevated ENOSF1 leaves affected
    cells severely thymidylate-synthase deficient with altered
    deoxyribonucleotide triphosphate pools, and the resulting genotoxic stress
    and defective transcription make telomere maintenance abnormal as a
    downstream consequence.
  biological_scale: MOLECULAR
  genes:
  - preferred_term: TYMS
    term:
      id: hgnc:12441
      label: TYMS
  - preferred_term: ENOSF1
    term:
      id: hgnc:30365
      label: ENOSF1
  cell_types:
  - preferred_term: Hematopoietic stem cell
    term:
      id: CL:0000037
      label: hematopoietic stem cell
  molecular_functions:
  - preferred_term: thymidylate synthase activity
    term:
      id: GO:0004799
      label: thymidylate synthase activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: deoxyribonucleoside triphosphate metabolic process
    term:
      id: GO:0009200
      label: deoxyribonucleoside triphosphate metabolic process
    modifier: ABNORMAL
  evidence:
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Lymphoblastoid cells from affected probands have severe TYMS deficiency,
      altered cellular deoxyribonucleotide triphosphate pools, and
      hypersensitivity to the TYMS-specific inhibitor 5-fluorouracil.
    explanation: >-
      Supports both bindings on this node: reduced thymidylate synthase activity and
      abnormal deoxyribonucleoside triphosphate metabolism, measured in patient cells.
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Gene-rescue studies in cells from affected probands revealed that
      post-transcriptional epistatic silencing of TYMS is occurring via elevated
      ENOSF1.
    explanation: >-
      Supports binding ENOSF1 to this node: it acts here by silencing TYMS rather than
      through a separate activity of its own.
  downstream:
  - target: Impaired Telomere Maintenance
    description: >-
      The nucleotide-pool defect produces genotoxic stress and defective
      transcription, and telomere maintenance becomes abnormal as a consequence,
      which is how this metabolic lesion joins the shared telomere pathograph.
    evidence:
    - reference: PMID:35931051
      reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        These defects in the nucleotide metabolism pathway resulted in genotoxic
        stress, defective transcription, and abnormal telomere maintenance.
      explanation: >-
        States the causal step from the nucleotide metabolic defect to abnormal telomere
        maintenance that this edge asserts.
- name: Apollo Exonuclease Deficiency
  description: >-
    In the DCLRE1B form the lesion is a hypomorphic 5'-to-3' DNA exonuclease.
    Patient cells show spontaneous chromosome instability and impaired DNA
    repair, complemented by correcting the gene, together with telomere
    fragility. Telomere length is not globally reduced, so this node does not
    feed the critically-short-telomere node that the telomerase, shelterin and
    CST lesions converge on; it reaches the same marrow failure by a
    genome-caretaker route instead.
  biological_scale: MOLECULAR
  genes:
  - preferred_term: DCLRE1B
    term:
      id: hgnc:17641
      label: DCLRE1B
  cell_types:
  - preferred_term: Hematopoietic stem cell
    term:
      id: CL:0000037
      label: hematopoietic stem cell
  molecular_functions:
  - preferred_term: exonuclease activity
    term:
      id: GO:0004527
      label: exonuclease activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: DNA repair
    term:
      id: GO:0006281
      label: DNA repair
    modifier: DECREASED
  evidence:
  - reference: PMID:35007328
    reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Apollo-deficient cells from patients exhibited spontaneous chromosome
      instability and impaired DNA repair that was complemented by
      CRISPR/Cas9-mediated gene correction.
    explanation: >-
      Supports the reduced DNA repair bound on this node, and the gene correction rules
      out an unrelated cause in those patient lines.
  - reference: PMID:35007328
    reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      patients' cells showed signs of telomere fragility that were not
      associated with global reduction of telomere length
    explanation: >-
      Supports treating this as a telomere-fragility rather than a telomere-shortening
      node, which is why it bypasses the critically-short-telomere node.
  downstream:
  - target: Stem Cell Exhaustion in High-Turnover Tissues
    description: >-
      Chromosome instability and telomere fragility in the absence of functional
      Apollo produce early-onset hypocellular bone marrow failure, entering the
      shared pathograph at the stem cell compartment rather than through
      telomere shortening.
    evidence:
    - reference: PMID:35007328
      reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We identified biallelic variants in the gene encoding the 5'-to-3' DNA
        exonuclease Apollo/SNM1B in 3 unrelated patients presenting with a DC/HH
        phenotype consisting of early-onset hypocellular bone marrow failure, B
        and NK lymphopenia, developmental anomalies, microcephaly, and/or
        intrauterine growth retardation.
      explanation: >-
        Records the early-onset hypocellular marrow failure that is the consequence this
        edge asserts.
- name: Critically Short Telomeres and Replicative Senescence
  description: >-
    Defective maintenance leads to progressive telomere attrition until telomeres
    become critically short or dysfunctional. Critically short telomeres are sensed
    as DNA damage, activating the p53/p21 DNA damage response and driving affected
    cells into replicative senescence or apoptosis, thereby limiting the replicative
    capacity of the tissue. Very short telomeres (often below the 1st percentile for
    age) are the diagnostic hallmark of DC.
  cell_types:
  - preferred_term: Hematopoietic stem cell
    term:
      id: CL:0000037
      label: hematopoietic stem cell
  biological_processes:
  - preferred_term: Replicative senescence
    term:
      id: GO:0090399
      label: replicative senescence
    modifier: INCREASED
  - preferred_term: Apoptotic process
    term:
      id: GO:0006915
      label: apoptotic process
    modifier: INCREASED
  - preferred_term: p53-mediated DNA damage response
    term:
      id: GO:0030330
      label: DNA damage response, signal transduction by p53 class mediator
    modifier: INCREASED
  evidence:
  - reference: PMID:39371255
    reference_title: "Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "telomeres shorten continuously with each cell division until critically short telomeres prevent further proliferation whereby cells undergo terminal differentiation, senescence, or apoptosis."
    explanation: Critically short telomeres halt proliferation and trigger senescence or apoptosis.
  - reference: PMID:40215293
    reference_title: "Loss of Ten1 in mice induces telomere shortening and models human dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Molecular analyses revealed a reduction of proliferating cells, increased apoptosis, and stem cell depletion with activation of the p53/p21 signaling pathway."
    explanation: Ten1-knockout mouse model demonstrates p53/p21 activation, apoptosis, and stem cell depletion from telomere dysfunction.
  downstream:
  - target: Stem Cell Exhaustion in High-Turnover Tissues
  - target: Predisposition to myelodysplastic syndrome and acute myeloid leukemia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Attached to the telomere/senescence node rather than to the downstream
      tissue-exhaustion node, because the route to malignancy is the genomic
      instability of critically short telomeres — chromosome-end fusion and
      breakage-fusion-bridge cycles — not the loss of stem-cell output itself.
      The two consequences of short telomeres diverge here: exhaustion produces
      the marrow failure, instability produces the clonal evolution.
  - target: Predisposition to squamous cell carcinoma
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The solid-tumour arm of the same genomic instability, arising
      characteristically in the head and neck and anogenital epithelia — the
      same high-turnover mucosal surfaces that carry the leukoplakia.
    evidence:
    - reference: PMID:20301779
      reference_title: Dyskeratosis Congenita and Related Telomere Biology Disorders.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        solid tumors (usually squamous cell carcinoma of the head/neck or
        anogenital cancer)
      explanation: >-
        Names the characteristic sites, which is what ties this predisposition
        to the mucosal surfaces affected elsewhere in the entry.
  - target: Cerebellar hypoplasia (Hoyeraal-Hreidarsson syndrome)
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      A feature of the severe end of the spectrum rather than of classic DC:
      Hoyeraal-Hreidarsson syndrome is the variant defined by the shortest
      telomeres and earliest onset. Linked from this node rather than from
      tissue exhaustion because it is developmental — the cerebellum is not a
      high-turnover tissue — and the mechanism by which telomere shortening
      produces it is not established.
    evidence:
    - reference: PMID:20301779
      reference_title: Dyskeratosis Congenita and Related Telomere Biology Disorders.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson
        syndrome)
      explanation: >-
        Records cerebellar hypoplasia as an additional finding naming the
        severe variant, which is the scope this edge asserts.
  - target: Exudative retinopathy (Revesz syndrome)
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The other severe-variant feature, defining Revesz syndrome, which dismech
      curates as its own entry. Same reasoning as the cerebellar feature: linked
      from the telomere node, with the mechanism unestablished.
    evidence:
    - reference: PMID:20301779
      reference_title: Dyskeratosis Congenita and Related Telomere Biology Disorders.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        bilateral exudative retinopathy and intracranial calcifications (Revesz
        syndrome and Coats plus syndrome)
      explanation: >-
        Names the exudative retinopathy and the severe variant it defines, from
        the same sentence already quoted on the neighbouring cerebellar edge.
- name: Stem Cell Exhaustion in High-Turnover Tissues
  description: >-
    Because telomere reserve restricts replicative capacity, tissues with high
    proliferative demand are preferentially affected. Premature replicative
    exhaustion of stem and progenitor cells in the bone marrow, immune system,
    skin and mucosa, liver, and lung produces the characteristic multisystem
    phenotype: bone marrow failure, mucocutaneous changes, and hepatic and
    pulmonary fibrosis. Genomic instability from dysfunctional telomeres also
    underlies the predisposition to myelodysplastic syndrome, leukemia, and
    squamous cell carcinoma.
  cell_types:
  - preferred_term: Hematopoietic stem cell
    term:
      id: CL:0000037
      label: hematopoietic stem cell
  - preferred_term: Hematopoietic precursor cell
    term:
      id: CL:0008001
      label: hematopoietic precursor cell
  - preferred_term: Pulmonary alveolar type 2 cell
    term:
      id: CL:0002063
      label: pulmonary alveolar type 2 cell
  evidence:
  - reference: PMID:39371255
    reference_title: "Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "altered telomere maintenance as observed in TBDs typically results in premature replicative cellular exhaustion in the respective organ systems eventually leading to life-threatening complications such as bone marrow failure (BMF), pulmonary fibrosis, and liver cirrhosis."
    explanation: Premature replicative exhaustion in high-turnover organs causes bone marrow failure, pulmonary fibrosis, and liver cirrhosis.
  downstream:
  - target: Bone marrow failure
    description: Exhaustion of hematopoietic stem and progenitor cells produces progressive bone marrow failure.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:39371255
      reference_title: "Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "premature replicative cellular exhaustion in the respective organ systems eventually leading to life-threatening complications such as bone marrow failure (BMF), pulmonary fibrosis, and liver cirrhosis."
      explanation: The review explicitly links premature cellular exhaustion in affected organs to bone marrow failure.
  - target: Pulmonary fibrosis
    description: Exhaustion of proliferative lung epithelial compartments contributes to telomere-biology-disorder pulmonary fibrosis.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:39371255
      reference_title: "Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "premature replicative cellular exhaustion in the respective organ systems eventually leading to life-threatening complications such as bone marrow failure (BMF), pulmonary fibrosis, and liver cirrhosis."
      explanation: The review explicitly links premature cellular exhaustion in affected organs to pulmonary fibrosis.
  - target: Hepatic fibrosis and portal hypertension
    description: Telomere-driven cellular exhaustion in liver tissue predisposes to fibrotic/cirrhotic liver disease.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:39371255
      reference_title: "Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "premature replicative cellular exhaustion in the respective organ systems eventually leading to life-threatening complications such as bone marrow failure (BMF), pulmonary fibrosis, and liver cirrhosis."
      explanation: The review explicitly links premature cellular exhaustion in affected organs to liver cirrhosis, supporting the hepatic fibrosis/cirrhosis branch.
  - target: Nail dystrophy
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      The nail bed is one of the high-turnover epithelia this node names, so
      nail dystrophy is the same exhaustion expressed in a different tissue as
      the marrow failure. It is the first component of the classic
      mucocutaneous triad.
    evidence:
    - reference: PMID:20301779
      reference_title: Dyskeratosis Congenita and Related Telomere Biology Disorders.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Classic DC is characterized by a triad of dysplastic nails, lacy
        reticular pigmentation of the upper chest and/or neck, and oral
        leukoplakia
      explanation: >-
        Establishes all three mucocutaneous components as the defining triad,
        which is the claim this and the following two edges make.
  - target: Reticular skin pigmentation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      The second component of the triad. Skin is a continuously renewing
      epithelium, and the lacy pigmentation of the upper chest and neck is the
      cutaneous form of the same stem-cell exhaustion.
    evidence:
    - reference: PMID:20301779
      reference_title: Dyskeratosis Congenita and Related Telomere Biology Disorders.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Classic DC is characterized by a triad of dysplastic nails, lacy
        reticular pigmentation of the upper chest and/or neck, and oral
        leukoplakia
      explanation: >-
        Names the reticular pigmentation and its characteristic distribution.
  - target: Oral leukoplakia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      The third component, in the oral mucosa — another high-turnover
      epithelium. It also matters beyond the triad, being the tissue from which
      the head-and-neck squamous carcinomas of this disease arise.
    evidence:
    - reference: PMID:20301779
      reference_title: Dyskeratosis Congenita and Related Telomere Biology Disorders.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Classic DC is characterized by a triad of dysplastic nails, lacy
        reticular pigmentation of the upper chest and/or neck, and oral
        leukoplakia
      explanation: >-
        Names oral leukoplakia as the third triad component.
  - target: Immunodeficiency
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Lymphocytes are among the most proliferative cells in the body, so the
      telomere reserve is exhausted there as it is in the marrow. The
      immunodeficiency of DC is therefore part of the same high-turnover
      failure rather than a separate lesion.
    evidence:
    - reference: PMID:39371255
      reference_title: "Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: >-
        a sufficient telomere reserve is particularly important in cells with
        high proliferative activity (e.g., hematopoiesis, immune cells,
        intestinal cells
      explanation: >-
        Places immune cells alongside haematopoiesis among the compartments
        dependent on telomere reserve, which is what this edge asserts.

phenotypes:
- category: Integumentary
  name: Nail dystrophy
  description: >-
    Dysplastic, dystrophic nails are a component of the classic DC mucocutaneous
    triad.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Nail dystrophy
    term:
      id: HP:0008404
      label: Nail dystrophy
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia"
    explanation: Dysplastic nails are part of the diagnostic DC triad.
  - reference: ORPHA:1775
    reference_title: "Dyskeratosis congenita"
    supports: SUPPORT
    snippet: "HP:0008404 | Nail dystrophy | Very frequent (99-80%)"
    explanation: Orphanet classifies nail dystrophy as very frequent in dyskeratosis congenita.
- category: Integumentary
  name: Reticular skin pigmentation
  description: >-
    Lacy/reticulated abnormal skin pigmentation, typically of the upper chest
    and/or neck, is a component of the classic DC mucocutaneous triad.
  phenotype_term:
    preferred_term: Reticulated skin pigmentation
    term:
      id: HP:0007427
      label: Reticulated skin pigmentation
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia"
    explanation: Lacy reticular pigmentation is part of the diagnostic DC triad.
  - reference: ORPHA:1775
    reference_title: "Dyskeratosis congenita"
    supports: SUPPORT
    snippet: "classic triad of nail dysplasia, skin pigmentary changes, and oral leukoplakia"
    explanation: Orphanet's definition supports pigmentary skin change as part of the classic DC triad.
- category: Oral
  name: Oral leukoplakia
  description: >-
    Oral leukoplakia is a component of the classic DC mucocutaneous triad and a
    site of increased risk for squamous cell carcinoma.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Oral leukoplakia
    term:
      id: HP:0002745
      label: Oral leukoplakia
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia"
    explanation: Oral leukoplakia is part of the diagnostic DC triad.
  - reference: ORPHA:1775
    reference_title: "Dyskeratosis congenita"
    supports: SUPPORT
    snippet: "HP:0002745 | Oral leukoplakia | Very frequent (99-80%)"
    explanation: Orphanet classifies oral leukoplakia as very frequent in dyskeratosis congenita.
- category: Hematologic
  name: Bone marrow failure
  description: >-
    Progressive bone marrow failure is a hallmark complication of DC and the
    leading cause of early mortality. Most children with classic DC progress to
    bone marrow failure.
  phenotype_term:
    preferred_term: Aplastic anemia
    term:
      id: HP:0001915
      label: Aplastic anemia
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "People with DC/TBD are at increased risk for progressive bone marrow failure (BMF)"
    explanation: Progressive bone marrow failure is a defining complication of DC.
  - reference: PMID:37593443
    reference_title: "Dyskeratosis congenita: natural history of the disease through the study of a cohort of patients diagnosed in childhood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thirteen progressed to bone marrow failure at a median age of 8 years"
    explanation: 13/14 children progressed to bone marrow failure at median age 8 years.
- category: Hematologic
  name: Bone marrow hypocellularity
  description: >-
    Bone marrow hypocellularity reflects hematopoietic stem cell exhaustion from
    telomere dysfunction.
  phenotype_term:
    preferred_term: Bone marrow hypocellularity
    term:
      id: HP:0005528
      label: Bone marrow hypocellularity
  reports_on:
  - target: Stem Cell Exhaustion in High-Turnover Tissues
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      The marrow-biopsy measurement of the haematopoietic arm of this node, distinct from the clinical bone marrow failure it underlies. An observational readout rather than a causal edge: the biopsy reports the state, it is not caused by it.
  evidence:
  - reference: PMID:39371255
    reference_title: "Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "altered telomere maintenance as observed in TBDs typically results in premature replicative cellular exhaustion in the respective organ systems eventually leading to life-threatening complications such as bone marrow failure (BMF)"
    explanation: Replicative exhaustion of marrow precursors leads to bone marrow failure and hypocellularity.
  - reference: ORPHA:1775
    reference_title: "Dyskeratosis congenita"
    supports: SUPPORT
    snippet: "HP:0005528 | Bone marrow hypocellularity | Frequent (79-30%)"
    explanation: Orphanet classifies bone marrow hypocellularity as frequent in dyskeratosis congenita.
- category: Respiratory
  name: Pulmonary fibrosis
  description: >-
    Pulmonary fibrosis / interstitial lung disease occurs in a substantial minority
    of DC patients and may be the presenting feature of cryptic adult-onset disease.
    Diagnostic surgical lung biopsy and empirical immunosuppression carry increased
    risk in unrecognized DC-associated pulmonary fibrosis.
  phenotype_term:
    preferred_term: Pulmonary fibrosis
    term:
      id: HP:0002206
      label: Pulmonary fibrosis
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis."
    explanation: Pulmonary fibrosis is a recognized DC complication.
  - reference: PMID:34479523
    reference_title: "Pulmonary fibrosis in dyskeratosis congenita: a case report with a PRISMA-compliant systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PF caused by DC should be kept in mind by clinicians in the differential diagnosis of patients with unexplained PF and should be excluded before diagnostic surgical lung biopsy is undertaken or empirical immunosuppression therapy is prescribed."
    explanation: DC-associated pulmonary fibrosis should be excluded before lung biopsy or immunosuppression.
- category: Hepatic
  name: Hepatic fibrosis and portal hypertension
  description: >-
    Liver involvement is common in DC, typically with a cholestatic pattern of
    liver enzyme elevation; a subset progresses to clinically significant liver
    disease and portal hypertension, especially in recessive or TINF2-associated DC.
  phenotype_term:
    preferred_term: Periportal fibrosis
    term:
      id: HP:0001405
      label: Periportal fibrosis
  evidence:
  - reference: PMID:37184208
    reference_title: "Progression of liver disease and portal hypertension in dyskeratosis congenita and related telomere biology disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Liver abnormality (defined at baseline assessment by laboratory and/or radiological findings) was present in 72.4% of patients with predominantly cholestatic pattern of liver enzyme elevation."
    explanation: Liver abnormality was present in 72.4% of DC/TBD patients with cholestatic pattern.
  - reference: PMID:37184208
    reference_title: "Progression of liver disease and portal hypertension in dyskeratosis congenita and related telomere biology disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinically significant liver disease and portal hypertension developed in 17.2% of patients during the 6-year follow-up; this progression was mainly seen in patients with recessive or TINF2 -associated DC."
    explanation: 17.2% progressed to clinically significant liver disease and portal hypertension.
- category: Neoplasm
  name: Predisposition to myelodysplastic syndrome and acute myeloid leukemia
  description: >-
    DC carries an increased risk of myelodysplastic syndrome and acute myeloid
    leukemia due to genomic instability and clonal evolution in the failing marrow.
  phenotype_term:
    preferred_term: Myelodysplasia
    term:
      id: HP:0002863
      label: Myelodysplasia
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia"
    explanation: DC predisposes to myelodysplastic syndrome and acute myeloid leukemia.
- category: Neoplasm
  name: Predisposition to squamous cell carcinoma
  description: >-
    DC patients are at increased risk of solid tumors, usually squamous cell
    carcinoma of the head and neck or anogenital region.
  phenotype_term:
    preferred_term: Squamous cell carcinoma
    term:
      id: HP:0002860
      label: Squamous cell carcinoma
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer)"
    explanation: DC predisposes to squamous cell carcinoma of the head/neck or anogenital region.
- category: Immunologic
  name: Immunodeficiency
  description: >-
    Immune dysfunction can occur in DC, reflecting telomere-driven exhaustion of
    the lymphoid compartment.
  phenotype_term:
    preferred_term: Immunodeficiency
    term:
      id: HP:0002721
      label: Immunodeficiency
  evidence:
  - reference: PMID:39371255
    reference_title: "Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a sufficient telomere reserve is particularly important in cells with high proliferative activity (e.g., hematopoiesis, immune cells, intestinal cells, liver, lung, and skin)."
    explanation: Immune cells require telomere reserve; telomere depletion compromises immune function.
- category: Neurologic
  name: Cerebellar hypoplasia (Hoyeraal-Hreidarsson syndrome)
  description: >-
    Cerebellar hypoplasia defines Hoyeraal-Hreidarsson syndrome, a severe
    early-onset DC variant.
  phenotype_term:
    preferred_term: Cerebellar hypoplasia
    term:
      id: HP:0001321
      label: Cerebellar hypoplasia
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome)"
    explanation: Cerebellar hypoplasia defines the Hoyeraal-Hreidarsson severe DC variant.
- category: Ophthalmologic
  name: Exudative retinopathy (Revesz syndrome)
  description: >-
    Bilateral exudative retinopathy (a Coats-like retinal vascular exudation
    process) with intracranial calcifications defines Revesz syndrome, a severe DC
    variant. Mapped to HP:0030490 (Exudative vitreoretinopathy), which captures the
    retinal vascular exudation underlying this phenotype more accurately than serous
    retinal detachment.
  phenotype_term:
    preferred_term: Exudative retinopathy
    term:
      id: HP:0030490
      label: Exudative vitreoretinopathy
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome"
    explanation: Bilateral exudative retinopathy defines the Revesz severe DC variant.

genetic:
- name: DKC1
  gene_term:
    preferred_term: DKC1
    term:
      id: hgnc:2890
      label: DKC1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: X-linked recessive inheritance
    inheritance_term:
      preferred_term: X-linked recessive inheritance
      term:
        id: HP:0001419
        label: X-linked recessive inheritance
  subtype: DKC1
  notes: >-
    DKC1 encodes dyskerin, an H/ACA snoRNP pseudouridine synthase required for
    stability of the telomerase RNA component; X-linked recessive, classically the
    most common and severe DC form.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists DKC1 among the 16 genes causing DC/TBD.
- name: TERT
  gene_term:
    preferred_term: TERT
    term:
      id: hgnc:11730
      label: TERT
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: TERT
  notes: >-
    TERT encodes the catalytic protein subunit of telomerase; variants cause DC and
    cryptic adult-onset TBD with pulmonary/hepatic fibrosis.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists TERT among the 16 genes causing DC/TBD.
- name: TERC
  gene_term:
    preferred_term: TERC
    term:
      id: hgnc:11727
      label: TERC
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  subtype: TERC
  notes: >-
    TERC encodes the telomerase RNA template subunit; autosomal dominant DC/TBD.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists TERC among the 16 genes causing DC/TBD.
- name: TINF2
  gene_term:
    preferred_term: TINF2
    term:
      id: hgnc:11824
      label: TINF2
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  subtype: TINF2
  notes: >-
    TINF2 encodes shelterin TIN2; autosomal dominant, often severe early-onset DC.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists TINF2 among the 16 genes causing DC/TBD.
- name: RTEL1
  gene_term:
    preferred_term: RTEL1
    term:
      id: hgnc:15888
      label: RTEL1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: RTEL1
  notes: >-
    RTEL1 encodes a telomere-replication helicase; dominant or recessive DC,
    including Hoyeraal-Hreidarsson syndrome.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists RTEL1 among the 16 genes causing DC/TBD.
- name: RTEL1-PFBMFT3
  gene_term:
    preferred_term: RTEL1
    term:
      id: hgnc:15888
      label: RTEL1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  subtype: PFBMFT3
  notes: >-
    The dominant, adult, pulmonary-led route into this entry through RTEL1,
    separated from the record above because the zygosity, age of onset and lead
    organ differ: heterozygous rare variants, adult onset, pulmonary fibrosis
    rather than the mucocutaneous triad. Penetrance is incomplete - unaffected
    heterozygous carriers in these families have short telomeres without lung
    disease - which is a property of this route specifically and not of the
    childhood recessive one. The mechanism ClinGen records for the gene as a whole
    is loss of function; the Genetic class carries no slot for that, so it is
    noted here.
  evidence:
  - reference: PMID:25607374
    reference_title: "Rare variants in RTEL1 are associated with familial interstitial pneumonia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Evaluation of affected individuals in 163 additional kindreds revealed another eight
      families (4.7%) with heterozygous rare variants in RTEL1 that segregated with clinical
      FIP.
    explanation: >-
      Source for the heterozygous, dominant transmission recorded on this record.
  - reference: PMID:25607374
    reference_title: "Rare variants in RTEL1 are associated with familial interstitial pneumonia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Probands and unaffected carriers of these rare variants had short telomeres (<10% for
      age) in peripheral blood mononuclear cells and increased T-circle formation, suggesting
      impaired RTEL1 function.
    explanation: >-
      Source for the incomplete-penetrance statement in the notes: carriers share
      the telomere phenotype without the lung disease.
- name: CTC1
  gene_term:
    preferred_term: CTC1
    term:
      id: hgnc:26169
      label: CTC1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: CTC1
  notes: >-
    CTC1 encodes a CST-complex subunit supporting telomere C-strand replication;
    autosomal recessive DC overlapping Coats plus.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists CTC1 among the 16 genes causing DC/TBD.
- name: RPA1
  gene_term:
    preferred_term: RPA1
    term:
      id: hgnc:10289
      label: RPA1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  subtype: RPA1
  notes: >-
    RPA1 encodes a single-stranded DNA-binding protein involved in telomere
    replication; autosomal dominant DC/TBD.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists RPA1 among the 16 genes causing DC/TBD.
- name: ACD
  gene_term:
    preferred_term: ACD
    term:
      id: hgnc:25070
      label: ACD
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: ACD
  notes: >-
    ACD encodes shelterin TPP1, which recruits and stimulates telomerase; dominant
    or recessive DC.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists ACD among the 16 genes causing DC/TBD.
- name: ACD-DKCA6
  gene_term:
    preferred_term: ACD
    term:
      id: hgnc:25070
      label: ACD
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  subtype: DKCA6
  notes: >-
    The dominant, OMIM-numbered ACD route into this entry, separated from the
    gene-level ACD record above because that record spans both inheritance
    modes. Curated for the heterozygous TEL-patch deletion p.Lys170del only. The
    lesion is a telomerase-recruitment defect rather than a loss of telomere
    binding: the mutant protein still localises to telomeres but no longer
    brings telomerase with it. The Genetic class carries no slot for that
    distinction, so it is recorded here.
  evidence:
  - reference: PMID:25205116
    reference_title: "Inherited bone marrow failure associated with germline mutation of ACD, the gene encoding telomere protein TPP1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we identify a family with aplastic anemia and other related hematopoietic disorders in which a 1-amino-acid deletion in the TEL patch of TPP1 (ΔK170) segregates with disease.
    explanation: >-
      The allele and its segregation with disease, which is the basis for the
      germline origin and dominant mode recorded here.
  - reference: PMID:25205116
    reference_title: "Inherited bone marrow failure associated with germline mutation of ACD, the gene encoding telomere protein TPP1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All family members carrying this mutation, but not those with wild-type TPP1, have short telomeres.
    explanation: >-
      Carrier status tracks with short telomeres, which is what makes the allele
      a telomere biology disorder allele rather than an incidental variant.
  - reference: PMID:25205116
    reference_title: "Inherited bone marrow failure associated with germline mutation of ACD, the gene encoding telomere protein TPP1."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      When introduced into 293T cells, TPP1 with the ΔK170 mutation is able to localize to telomeres but fails to recruit telomerase to telomeres, supporting a causal relationship between this TPP1 mutation and bone marrow disorders.
    explanation: >-
      The cell-based experiment behind the recruitment-versus-binding
      distinction recorded in this record's notes; a 293T transfection, not a
      measurement in patient cells.
- name: NHP2
  gene_term:
    preferred_term: NHP2
    term:
      id: hgnc:14377
      label: NHP2
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: NHP2
  notes: >-
    NHP2 encodes an H/ACA snoRNP component required for telomerase RNA stability;
    autosomal recessive DC.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists NHP2 among the 16 genes causing DC/TBD.
- name: NOP10
  gene_term:
    preferred_term: NOP10
    term:
      id: hgnc:14378
      label: NOP10
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: NOP10
  notes: >-
    NOP10 encodes an H/ACA snoRNP component required for telomerase RNA stability;
    autosomal recessive DC.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists NOP10 among the 16 genes causing DC/TBD.
- name: PARN
  gene_term:
    preferred_term: PARN
    term:
      id: hgnc:8609
      label: PARN
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: PARN
  notes: >-
    PARN encodes a deadenylase required for TERC maturation; dominant or recessive
    DC, associated with pulmonary fibrosis.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists PARN among the 16 genes causing DC/TBD.
- name: WRAP53
  gene_term:
    preferred_term: WRAP53
    term:
      id: hgnc:25522
      label: WRAP53
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: WRAP53
  notes: >-
    WRAP53 (TCAB1) traffics telomerase to Cajal bodies; autosomal recessive DC.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists WRAP53 among the 16 genes causing DC/TBD.
- name: POT1
  gene_term:
    preferred_term: POT1
    term:
      id: hgnc:17284
      label: POT1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: POT1
  notes: >-
    POT1 encodes a shelterin protein binding telomeric single-stranded DNA;
    pathogenic variants reduce ssDNA binding and expand the DC allelic series.
  evidence:
  - reference: PMID:39198715
    reference_title: "The evolving genetic landscape of telomere biology disorder dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we have also identified several novel variants in POT1 and ZCCHC8 in multiple cases from different families expanding the allelic series of DC and DCL phenotypes."
    explanation: Novel POT1 variants expand the DC allelic series.
- name: POT1-PFBMFT8
  gene_term:
    preferred_term: POT1
    term:
      id: hgnc:17284
      label: POT1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  subtype: PFBMFT8
  notes: >-
    The second, dominant POT1 route into this entry, separated from the
    recessive POT1 record above because the allele, the zygosity and the
    clinical presentation all differ. Curated for the heterozygous p.(L259S)
    allele only. The allele behaves as a dominant negative rather than a simple
    null, but that classification rests on the knock-in mouse, in which
    telomerase overexpression fails to lengthen telomeres in the presence of the
    mutant protein; the Genetic class carries no slot for it, so it is recorded
    here.
  evidence:
  - reference: PMID:35420632
    reference_title: >-
      Telomere dysfunction implicates POT1 in patients with idiopathic pulmonary fibrosis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Familial pulmonary fibrosis caused by a telomere-related gene mutation is usually an autosomal dominant disease.
    explanation: >-
      Source for the dominant inheritance recorded on this record.
  - reference: PMID:40954016
    reference_title: >-
      Mice carrying the homologous human shelterin POT1-L259S mutation linked to pulmonary fibrosis show a telomerase deficiency-like phenotype with telomere shortening with increasing mouse generations.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Importantly, overexpression of telomerase in adult Pot1aL261S/L261S mice did not lead to telomere lengthening, suggesting that the POT1a-L261S mutant protein is blocking the activity of telomerase-elongating telomeres and acts as a dominant negative.
    explanation: >-
      The experiment behind the DOMINANT_NEGATIVE functional impact recorded
      here; note it is a mouse result, not a measurement in patient cells.
- name: POLA1
  gene_term:
    preferred_term: POLA1
    term:
      id: hgnc:9173
      label: POLA1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: X-linked recessive inheritance
    inheritance_term:
      preferred_term: X-linked recessive inheritance
      term:
        id: HP:0001419
        label: X-linked recessive inheritance
  notes: >-
    POLA1 (DNA polymerase alpha catalytic subunit) was newly implicated as an
    X-linked DC gene in 2024; pathogenic variants disrupt protein-protein
    interactions with primase, the CST complex, and shelterin that are critical for
    telomere maintenance.
  evidence:
  - reference: PMID:39198715
    reference_title: "The evolving genetic landscape of telomere biology disorder dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This led us to identify several novel pathogenic variants within known genetic loci and in the novel X-linked gene, POLA1."
    explanation: POLA1 is a newly identified X-linked DC gene.
  - reference: PMID:39198715
    reference_title: "The evolving genetic landscape of telomere biology disorder dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Functional characterisation of novel POLA1 and POT1 variants, revealed pathogenic effects on protein-protein interactions with primase, CTC1-STN1-TEN1 (CST) and shelterin subunit complexes, that are critical for telomere maintenance."
    explanation: Functional studies show POLA1 variants disrupt CST/shelterin/primase interactions required for telomere maintenance.
- name: NAF1
  gene_term:
    preferred_term: NAF1
    term:
      id: hgnc:25126
      label: NAF1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  subtype: NAF1
  notes: >-
    NAF1 encodes an H/ACA ribonucleoprotein assembly factor required for biogenesis
    and stability of the telomerase RNA component (TERC).
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists NAF1 among the 16 genes causing DC/TBD.
- name: STN1
  gene_term:
    preferred_term: STN1
    term:
      id: hgnc:26200
      label: STN1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  subtype: STN1
  notes: >-
    STN1 encodes a subunit of the CST (CTC1-STN1-TEN1) complex required for telomere
    replication and C-strand fill-in synthesis.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists STN1 among the 16 genes causing DC/TBD.
- name: ZCCHC8
  gene_term:
    preferred_term: ZCCHC8
    term:
      id: hgnc:25265
      label: ZCCHC8
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
  subtype: ZCCHC8
  notes: >-
    ZCCHC8 encodes a component of the nuclear exosome targeting (NEXT) complex
    involved in processing and quality control of the telomerase RNA component.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ACD, CTC1, DKC1, NAF1, NHP2, NOP10, PARN, POT1, RPA1, RTEL1, STN1, TERC, TERT, TINF2, WRAP53, and ZCCHC8 are the genes in which pathogenic variants are known to cause DC/TBD"
    explanation: GeneReviews lists ZCCHC8 among the 16 genes causing DC/TBD.
  - reference: PMID:39198715
    reference_title: "The evolving genetic landscape of telomere biology disorder dyskeratosis congenita."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we have also identified several novel variants in POT1 and ZCCHC8 in multiple cases from different families expanding the allelic series of DC and DCL phenotypes."
    explanation: Novel ZCCHC8 variants expand the DC allelic series.

- name: TYMS
  association: Loss of function
  subtype: DKCD
  gene_term:
    preferred_term: TYMS
    term:
      id: hgnc:12441
      label: TYMS
  notes: >-
    TYMS is the first of the two loci in the digenic form. Affected probands
    carry a heterozygous germline TYMS coding variant inherited from one parent;
    disease appears only when the ENOSF1 haplotype is inherited in trans.
  evidence:
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In a cohort of eight independent DC-affected families, we have identified
      a remarkable series of heterozygous germline variants in the gene encoding
      thymidylate synthase (TYMS).
    explanation: >-
      Establishes germline TYMS variants in eight DC families.
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Lymphoblastoid cells from affected probands have severe TYMS deficiency,
      altered cellular deoxyribonucleotide triphosphate pools, and
      hypersensitivity to the TYMS-specific inhibitor 5-fluorouracil.
    explanation: >-
      Confirms the loss-of-function consequence recorded on this record, measured in
      patient-derived cells.
- name: ENOSF1
  association: Modifier
  relationship_type: COOPERATING
  subtype: DKCD
  gene_term:
    preferred_term: ENOSF1
    term:
      id: hgnc:30365
      label: ENOSF1
  notes: >-
    ENOSF1 is the antisense regulator of TYMS and the second locus of the
    digenic form. The disease-associated haplotype acts by raising ENOSF1 so that
    TYMS is silenced post-transcriptionally, which is why it is recorded as a
    cooperating locus rather than as an independently causative gene.
  evidence:
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Targeted genomic sequencing identified a specific haplotype and rare
      variants in the naturally occurring TYMS antisense regulator ENOSF1
      (enolase super family 1) inherited from the other parent.
    explanation: >-
      Establishes the ENOSF1 haplotype as the trans-inherited second locus.
  - reference: PMID:35931051
    reference_title: Germline thymidylate synthase deficiency impacts nucleotide metabolism and causes dyskeratosis congenita.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Gene-rescue studies in cells from affected probands revealed that
      post-transcriptional epistatic silencing of TYMS is occurring via elevated
      ENOSF1.
    explanation: >-
      Supports the cooperating, epistatic mechanism recorded on this record rather than a
      direct loss of ENOSF1 function.
- name: DCLRE1B
  association: Loss of function
  subtype: DCLRE1B
  gene_term:
    preferred_term: DCLRE1B
    term:
      id: hgnc:17641
      label: DCLRE1B
  notes: >-
    DCLRE1B encodes the 5'-to-3' DNA exonuclease Apollo/SNM1B. All three
    reported patients carry a missense variant at the catalytic-domain residue
    L142, homozygous or compound heterozygous with a null allele. Human Apollo
    KO cell lines show strong telomere dysfunction with excessive shortening
    while patient cells do not, which is the basis for calling the patient
    alleles hypomorphic.
  evidence:
  - reference: PMID:35007328
    reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We identified biallelic variants in the gene encoding the 5'-to-3' DNA
      exonuclease Apollo/SNM1B in 3 unrelated patients presenting with a DC/HH
      phenotype consisting of early-onset hypocellular bone marrow failure, B
      and NK lymphopenia, developmental anomalies, microcephaly, and/or
      intrauterine growth retardation.
    explanation: >-
      Establishes biallelic DCLRE1B variants as causal in three unrelated patients with a
      DC/Hoyeraal-Hreidarsson phenotype.
  - reference: PMID:35007328
    reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      identify biallelic Apollo variants as a genetic cause of a hitherto
      unrecognized severe IBMFS that combines clinical hallmarks of DC/HH with
      normal telomere length
    explanation: >-
      Records the normal telomere length that makes this gene an exception to the entry's
      short-telomere diagnostic criterion.
  - reference: PMID:35007328
    reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All 3 patients carry a homozygous or compound heterozygous (in combination
      with a null allele) missense variant affecting the same residue L142 (L142F
      or L142S) located in the catalytic domain of Apollo.
    explanation: >-
      Source for the recurrent catalytic-domain residue and the biallelic configuration
      recorded in the notes on this record.
  - reference: PMID:35007328
    reference_title: Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      human Apollo KO HT1080 cell lines showed strong telomere dysfunction
      accompanied by excessive telomere shortening, suggesting that the L142S and
      L142F Apollo variants are hypomorphic
    explanation: >-
      Source for calling the patient alleles hypomorphic: a full knockout shortens
      telomeres where the patient alleles do not.
animal_models:
- name: Pot1a L261S knock-in mouse
  species: Mouse
  genotype: Pot1a L261S knock-in (homozygous and heterozygous), homologous to human POT1 p.L259S
  publication: PMID:40954016
  description: >-
    A humanised knock-in of the murine residue homologous to the human POT1
    L259S allele of the PFBMFT8 subtype. Homozygotes progressively shorten
    their telomeres across successive mouse generations and develop degenerative
    intestinal, testicular and lung pathology at old age, phenocopying the
    telomerase-knockout mouse.
  modeled_mechanisms:
  - target: Impaired Telomere Maintenance
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      The knock-in reproduces the upstream lesion of this entry: telomerase
      activity at telomeres falls in the presence of the mutant protein and
      telomeres shorten with successive generations.
    limitations: >-
      The generational phenotype requires homozygosity, whereas human PFBMFT8
      carriers are heterozygous; heterozygous mice show only a trend toward
      shorter telomeres. Mouse telomeres are far longer than human telomeres,
      which is why several generations of intercross are needed before a
      phenotype appears at all.
    readouts:
    - name: Telomere length by telomeric Q-FISH across mouse generations
      target: Impaired Telomere Maintenance
      direction: DECREASED
      interpretation: >-
        Direct measure of the telomere-maintenance deficit modelled by this
        link.
      evidence:
      - reference: PMID:40954016
        reference_title: >-
          Mice carrying the homologous human shelterin POT1-L259S mutation linked to pulmonary fibrosis show a telomerase deficiency-like phenotype with telomere shortening with increasing mouse generations.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          We found that the homozygous Pot1a L261S mice show shorter telomeres and degenerative pathologies in the intestine, testes, and lungs at old ages, a phenotype that is aggravated with increasing mouse generations, in striking analogy to the telomerase-deficient mouse models.
        explanation: >-
          Reports the shortened telomeres and their aggravation across
          generations that this readout records.
    evidence:
    - reference: PMID:40954016
      reference_title: >-
        Mice carrying the homologous human shelterin POT1-L259S mutation linked to pulmonary fibrosis show a telomerase deficiency-like phenotype with telomere shortening with increasing mouse generations.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        We show that telomerase activity at telomeres is reduced in the presence of POT1a-L261S, which behaves as a dominant negative mutant, thus providing a potential mechanism by which Pot1a L261S knock-in mice phenocopy the short telomere phenotype of the telomerase knockout model.
      explanation: >-
        Establishes the model as informative for the impaired telomere
        maintenance node.
  - target: Pulmonary fibrosis
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      Old knock-in mice develop profibrotic lung pathology - alveolar septal
      thickening, inflammatory infiltrate and increased alpha-smooth muscle
      actin - but this stops short of the established fibrosis that defines the
      human phenotype.
    limitations: >-
      Masson trichrome staining found no significant difference in lung
      collagen between knock-in and wild-type animals; only a single G3
      homozygote reached extensive collagen deposition. So the model reproduces
      a profibrotic tendency, not idiopathic pulmonary fibrosis, and it does so
      only in homozygotes at old age.
    readouts:
    - name: Alpha-smooth muscle actin positive myofibroblasts in lung
      target: Pulmonary fibrosis
      direction: INCREASED
      interpretation: >-
        Activated myofibroblasts are the collagen-secreting cells of the
        fibrotic response, so their increase is the profibrotic signal this
        model does show.
      evidence:
      - reference: PMID:40954016
        reference_title: >-
          Mice carrying the homologous human shelterin POT1-L259S mutation linked to pulmonary fibrosis show a telomerase deficiency-like phenotype with telomere shortening with increasing mouse generations.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          The G2–G3 Pot1a-L261S knock-in and G3 Tert knockout lungs presented higher incidence of α-smooth muscle actin (SMA), a marker of activated myofibroblasts, which are collagen-secreting cells implicated in tissue repair
        explanation: >-
          The myofibroblast measurement behind this readout.
    - name: Lung collagen content by Masson trichrome staining
      target: Pulmonary fibrosis
      direction: UNCHANGED
      interpretation: >-
        The negative result that caps this link at PARTIALLY_RECAPITULATES:
        established fibrosis was not reproduced at the group level.
      evidence:
      - reference: PMID:40954016
        reference_title: >-
          Mice carrying the homologous human shelterin POT1-L259S mutation linked to pulmonary fibrosis show a telomerase deficiency-like phenotype with telomere shortening with increasing mouse generations.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          In this regard, we next analyzed the incidence of fibrosis in the lungs by Masson trichrome staining, and although we did not find significant differences between G2 and G3 Pot1a-L261S knock-in and wild-type lungs, one G3 Pot1aL261S/L261S mouse presented with >50% of its lung area covered by collagen fibers (Fig.
        explanation: >-
          Reports the absence of a group-level collagen difference, with a
          single outlier animal.
    evidence:
    - reference: PMID:40954016
      reference_title: >-
        Mice carrying the homologous human shelterin POT1-L259S mutation linked to pulmonary fibrosis show a telomerase deficiency-like phenotype with telomere shortening with increasing mouse generations.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        The fact that 80% of the G2 Pot1aL261S/L261S and 50% of the G3 Pot1aL261S/L261S and G3 Tert−/− mice presented with inflammatory phenotype with focal thickening of the alveolar septa and an augmented presence of myofibroblasts and some mice had elevated content of collagen depots in their lungs
      explanation: >-
        The authors' own count of how far the lung phenotype goes: an
        inflammatory, myofibroblast-rich profibrotic picture in most old
        homozygotes, with frank collagen deposition only in some.

treatments:
- name: Hematopoietic stem cell transplantation
  description: >-
    Hematopoietic cell transplantation is the only curative treatment for bone
    marrow failure and leukemia in DC, but historically has poor long-term outcome
    due to treatment toxicity. Radiation- and alkylator-reduced conditioning is
    favored, and related donors carrying the familial variant should be avoided.
  treatment_term:
    preferred_term: hematopoietic stem cell transplantation
    term:
      id: NCIT:C15431
      label: Hematopoietic Cell Transplantation
  therapeutic_modality: CELL_THERAPY
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hematopoietic cell transplantation (HCT) is the only curative treatment for BMF and leukemia, but long-term outcome has historically been poor due to treatment toxicity"
    explanation: HCT is the only curative treatment for DC marrow failure/leukemia but is toxicity-limited.
  target_mechanisms:
  - target: Stem Cell Exhaustion in High-Turnover Tissues
    treatment_effect: MODULATES
    description: >-
      HSCT replaces the dysfunctional short-telomere hematopoietic stem cell
      pool with donor-derived cells, rescuing hematopoiesis and reducing
      leukemia risk; it does not correct the underlying telomere maintenance
      defect in non-hematopoietic tissues.
- name: Androgen therapy (danazol)
  description: >-
    Androgen therapy (e.g., danazol, oxymetholone) can improve blood counts and may
    be considered for bone marrow failure when a suitable transplant donor is not
    available. The combination of androgens with granulocyte colony-stimulating
    factor should be avoided because it has been associated with splenic rupture;
    monitoring of CBC, liver function, and liver ultrasound is recommended.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: danazol
      term:
        id: CHEBI:4315
        label: danazol
    - preferred_term: oxymetholone
      term:
        id: CHEBI:7864
        label: oxymetholone
  therapeutic_modality: SMALL_MOLECULE
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "if a suitable donor is not available, androgen therapy may be considered for BMF."
    explanation: Androgen therapy is an option for bone marrow failure when transplant is not available.
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the combination of androgens and granulocyte colony-stimulating factor in treatment of BMF (has been associated with splenic rupture)"
    explanation: GeneReviews Agents/Circumstances to Avoid - androgen plus G-CSF risks splenic rupture.
  target_mechanisms:
  - target: Impaired Telomere Maintenance
    treatment_effect: MODULATES
    description: >-
      Androgens (danazol, oxymetholone) upregulate TERT expression, boosting
      telomerase activity in hematopoietic progenitors and partially reversing
      the telomere maintenance defect.
  - target: Critically Short Telomeres and Replicative Senescence
    treatment_effect: MODULATES
    description: >-
      By stimulating TERT, androgen therapy can slow the rate of telomere
      attrition in bone marrow progenitors, delaying progression to replicative
      senescence and improving blood counts.
- name: Lung transplantation
  description: >-
    Treatment of pulmonary fibrosis is primarily supportive, although lung
    transplantation may be considered for end-stage disease.
  treatment_term:
    preferred_term: organ transplantation
    term:
      id: NCIT:C15289
      label: Organ Transplantation
  therapeutic_modality: SURGERY
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Treatment of pulmonary fibrosis is primarily supportive, although lung transplantation may be considered."
    explanation: Lung transplantation may be considered for DC-associated pulmonary fibrosis.
  target_mechanisms:
  - target: Stem Cell Exhaustion in High-Turnover Tissues
    treatment_effect: MODULATES
    description: >-
      Lung transplantation replaces end-stage fibrotic lung tissue; it does not
      address the underlying telomere biology defect and DC patients face
      elevated post-transplant risks from impaired regenerative capacity in
      other high-turnover tissues.
- name: Cancer surveillance and supportive care
  description: >-
    Surveillance is central to DC management, including annual CBC and bone marrow
    evaluation, monthly oral/head/neck self-examination with annual otolaryngology
    and dermatology screening, and annual pulmonary function tests. Of note, cancer
    therapy may pose an increased risk of prolonged cytopenias and pulmonary and
    hepatic toxicity, and non-irradiated/leukodepleted blood products should be used.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "cancer therapy may pose an increased risk for prolonged cytopenias as well as pulmonary and hepatic toxicity."
    explanation: GeneReviews notes increased risk from cancer therapy, motivating surveillance and supportive care.
  - reference: PMID:39048762
    reference_title: "MASCC/ISOO Clinical Practice Statement: The risk of secondary oral cancer following hematopoietic cell transplantation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Studies described a 7-16-fold higher risk of secondary oral cancer (mainly squamous cell carcinoma) in allogeneic HCT (alloHCT) recipients, particularly in those who developed chronic graft versus host disease (cGVHD)."
    explanation: The MASCC/ISOO statement quantifies the markedly elevated secondary oral cancer risk after allogeneic HCT, reinforcing oral-cancer surveillance in transplanted DC patients.
  - reference: PMID:28533057
    reference_title: "Late Effects Screening Guidelines after Hematopoietic Cell Transplantation for Inherited Bone Marrow Failure Syndromes: Consensus Statement From the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects After Pediatric HCT."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "This companion article outlines consensus disease-specific long-term follow-up screening guidelines for patients with IMBFS."
    explanation: Consensus late-effects screening guidelines for inherited bone marrow failure syndromes (which include dyskeratosis congenita) frame long-term post-transplant surveillance.
- name: Genetic counseling
  description: >-
    Genetic counseling addresses gene-specific mode of inheritance; once the
    familial variant is identified, prenatal and preimplantation genetic testing
    are possible. Family members should not donate blood if HCT is being considered,
    and potential related donors require telomere length and/or molecular testing.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Once the DC/TBD-related pathogenic variant(s) have been identified in an affected family member, prenatal and preimplantation genetic testing are possible."
    explanation: Genetic counseling enables prenatal/preimplantation testing once the variant is known.

discussions:
- discussion_id: gap_dc_unexplained_genetic_cause
  prompt: >-
    What accounts for the roughly 20% of clinically diagnosed dyskeratosis
    congenita / telomere biology disorder cases in which no pathogenic variant is
    identified in any of the 16 known DC/TBD genes?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Impaired Telomere Maintenance
  rationale: >-
    GeneReviews reports that pathogenic variants in the 16 known DC/TBD genes are
    identified in approximately 80% of individuals meeting clinical diagnostic
    criteria, leaving roughly one in five clinically diagnosed patients genetically
    unexplained. These cases likely harbor variants in undiscovered genes,
    non-coding or structural variants in known loci, or somatic/mosaic events not
    captured by standard testing. Resolving this gap would extend the mechanistic
    chain (impaired telomere maintenance) to currently uncharacterized molecular
    causes and improve molecular diagnosis and counseling.
  evidence:
  - reference: PMID:20301779
    reference_title: "Dyskeratosis Congenita and Related Telomere Biology Disorders."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "in approximately 80% of individuals who meet"
    explanation: >-
      GeneReviews reports a genetic diagnostic yield of approximately 80%,
      implying roughly 20% of clinically diagnosed DC/TBD remains genetically
      unexplained.
datasets:
- accession: ega:EGAS50000001644
  title: RTEL1 mutation as a modifier of Dyskeratosis Congenita in a family with a Telomerase RNA (hTR) template mutation and variant telomeric repeats
  description: Vertebrate telomeres, the sequences protecting the end of linear chromosomes, are composed of conserved hexameric GGTTAG repeats. Here we present a C50>A telomerase RNA template mutation that results in the incorporation of the variant telomeric repeat GTTTAG in a family with dyskeratosis congenita primarily presenting as idiopathic pulmonary fibrosis. The mutant telomerase is characterized by decreased processivity in direct telomerase activity assays and in vivo based on data from Illumina next-generation whole genome sequencing and Oxford Nanopore Technologies long-read telomere sequencing.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: WGS
  notes: 'European Genome-phenome Archive study, matched because the disease is named in the study''s own title ("Dyskeratosis Congenita"); description-level mentions were not accepted. EGA study_type: Whole Genome Sequencing. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.'

📚

References & Deep Research

References

PMID:20301779

Dyskeratosis Congenita and Related Telomere Biology Disorders.

No top-level findings curated for this source.

Deep Research

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.

Falcon ▸

Disease Characteristics Research Template

Edison Scientific Literature 47 citations 2026-06-05T14:39:23.053674

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

Disease Name: Dyskeratosis Congenita
MONDO ID: (if available)
Category: Mendelian

Research Objectives

Please provide a comprehensive research report on Dyskeratosis Congenita covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

What is the disease? Provide a concise overview.
What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
What are the common synonyms and alternative names?
Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
Risk Factors:

Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases
Genetic risk factors (causal variants, susceptibility loci, modifier genes)
Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
Protective Factors:

Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases
Genetic protective factors (protective variants, modifier alleles)
Environmental protective factors (diet, lifestyle, exposures that reduce risk)
Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene
Pathogenic Variants:
Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
Variant type/class (missense, frameshift, nonsense, splice-site, structural)
Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
Functional consequences (loss of function, gain of function, dominant negative)
Modifier Genes: Genes that modify disease severity or expression
Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases
Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

Search first: CDC databases, WHO, PubMed, NHANES
Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc
Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

Search first: Gene Ontology (GO), Reactome, KEGG, PubMed
Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold
Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA
Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

Search first: ImmPort, Immunome Database, IEDB, Gene Ontology
Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

Search first: PubMed, Gene Ontology, Reactome
Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

Search first: BRENDA, UniProt, KEGG, OMIM, PubMed
Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Molecular Profiling (if available):
Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
Advanced Technologies (if applicable):
Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

Organ Level:
Primary organs directly affected
Secondary organ involvement (complications, secondary effects)
Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT
Tissue and Cell Level:
Specific tissue types affected (epithelial, connective, muscle, nervous)
Specific cell populations targeted (with Cell Ontology terms)

Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB
Subcellular Level:
Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas
Localization:
Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

Onset:
Typical age of onset (congenital, pediatric, adult, geriatric)
Onset pattern (acute, subacute, chronic, insidious)

Search first: OMIM, Orphanet, HPO, PubMed
Progression:
Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
Progression rate (rapid, slow, variable)
Disease course pattern (episodic, relapsing-remitting, progressive, stable)
Disease duration (self-limited, chronic lifelong)

Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM
Patterns:
Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

Epidemiology:
Prevalence (cases per 100,000 at given time)
Incidence (new cases per 100,000 per year)

Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries
For Genetic Etiology:
Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
Population Demographics:
Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
Geographic distribution of specific variants
Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

Clinical Tests:
Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
Genetic Testing:

Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen
Overview of recommended genetic testing approach
Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
FISH > Search first: ClinVar, cytogenetics databases, PubMed
Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
Omics-Based Diagnostics (if applicable):
RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
Clinical Criteria:
Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
Screening:
Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

Survival and Mortality:
Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
Morbidity and Function:
Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
Disease Course:
Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
Prediction:
Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

Pharmacotherapy:
Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
Advanced Therapeutics:
Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
Surgical and Interventional:
Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
Supportive and Rehabilitative:
Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
Experimental:
Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
Treatment Outcomes:
Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
Treatment Strategy:
Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest MAXO (Medical Action Ontology) terms where applicable.

13. Prevention

Prevention Levels:
Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
Immunization: Vaccine strategies (if applicable)

Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database
Screening and Early Detection:
Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
Behavioral Interventions: Lifestyle modifications to reduce risk

Search first: CDC, WHO, behavioral intervention databases, Cochrane Library
Counseling: Genetic counseling (risk assessment, family planning guidance)

Search first: NSGC resources, ACMG guidelines, GeneReviews
Public Health:
Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
Prophylaxis: Preventive medications or procedures

Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

Taxonomy: Species affected (with NCBI Taxon identifiers)

Search first: NCBI Taxonomy
Breed: Specific breeds affected (with VBO identifiers if applicable)

Search first: VBO (Vertebrate Breed Ontology)
Gene: Orthologous genes in other species (with NCBI Gene IDs)

Search first: NCBI Gene
Natural Disease:
Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
Comparative Biology:
Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
Transmission (if applicable):
Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

Model Types:
Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
Genetic Models:
Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
Model Characteristics:
Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
Applications:
Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
Resources:
Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

Cite primary literature (PMID preferred) for all mechanistic and clinical claims
Prioritize recent reviews and landmark papers
Include direct quotes from abstracts where possible to support key statements
Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Dyskeratosis Congenita (DC) — Comprehensive Disease Characteristics Report (Mendelian)

Target disease: Dyskeratosis congenita (DC)
Category: Mendelian / inherited bone marrow failure syndrome; telomere biology disorder (TBD) / short-telomere syndrome (niewisch2023clinicalmanifestationsof pages 1-2, rolles2024inheritedtelomerebiology pages 8-9).
MONDO ID: Not available in the retrieved full-text evidence in this run (mazurek2023dyskeratosiscongenitaas pages 4-5).

Executive summary

Dyskeratosis congenita is an ultra-rare inherited, multisystem disorder within the telomere biology disorders spectrum, classically defined by the mucocutaneous triad of nail dystrophy, abnormal/reticulated skin pigmentation, and oral leukoplakia, and complicated by progressive bone marrow failure and increased malignancy and fibrotic organ disease risk (koldej2023dyskeratosiscongenitanatural pages 1-2, rolles2024inheritedtelomerebiology pages 8-9, niewisch2023clinicalmanifestationsof pages 1-2). Contemporary understanding frames DC as a disorder of impaired telomere maintenance, in which germline pathogenic variants across telomerase, shelterin, CST/replication, and telomerase RNA processing/trafficking pathways cause telomere shortening/dysfunction leading to stem cell exhaustion and tissue failure (revy2023geneticsofhuman pages 5-8, rolles2024inheritedtelomerebiology pages 8-9, mazurek2023dyskeratosiscongenitaas pages 1-2).

A recent 2024 high-impact genetic study expanded DC’s genetic architecture (including a newly implicated X-linked gene POLA1 and expanded allelic series in POT1 and ZCCHC8) and emphasized that a substantial fraction of clinically diagnosed cases remain genetically unresolved (tummala2024theevolvinggenetic pages 1-2, tummala2024theevolvinggenetic pages 3-5).

Domain	Summary
Identifiers/synonyms	- Dyskeratosis congenita (DC) is also referred to as Zinsser–Cole–Engman syndrome in retrieved sources. - It is classified as a telomere biology disorder (TBD) / short-telomere syndrome. - Formal OMIM, Orphanet, ICD-10/11, MeSH, MONDO codes were not in retrieved full-text evidence. (ayas2026dyskeratosiscongenita pages 1-4, mazurek2023dyskeratosiscongenitaas pages 4-5, niewisch2023clinicalmanifestationsof pages 1-2)
Core definition	- DC is an ultra-rare inherited multisystem bone marrow failure syndrome caused principally by defects in telomere maintenance. - The classic diagnostic triad is nail dystrophy, abnormal/reticulated skin pigmentation, and oral leukoplakia. - Bone marrow failure and cancer predisposition are central disease-defining complications. (koldej2023dyskeratosiscongenitanatural pages 1-2, tummala2024theevolvinggenetic pages 1-2, rolles2024inheritedtelomerebiology pages 8-9, niewisch2023clinicalmanifestationsof pages 1-2)
Key phenotypes & frequencies	- Mucocutaneous triad frequencies reported in one 2023 review: reticulated pigmentation ~90%, nail dystrophy ~88%, leukoplakia ~80%. - Bone marrow failure is a hallmark; some sources report >90% by age 40. - Extra-hematologic disease includes pulmonary fibrosis/interstitial lung disease, liver disease/portal hypertension, premature hair graying, and cancer susceptibility; pulmonary fibrosis occurs in about 20% in one review. (mazurek2023dyskeratosiscongenitaas pages 4-5, ayas2026dyskeratosiscongenita pages 1-4, wang2021pulmonaryfibrosisin pages 1-2, vittal2023progressionofliver pages 1-2, franke2025diagnosisandmanagement pages 7-10)
Natural history stats	- In a pediatric cohort (n=14), diagnosis occurred at median age 8.5 years; 13/14 progressed to bone marrow failure at median age 8 years. - In the same cohort, 6/14 died, at median age 13 years; all had hematologic manifestations at diagnosis and non-hematologic manifestations accumulated over follow-up. - Adult/cryptic TBD can present later with isolated hematologic, pulmonary, or liver disease rather than the full triad. (koldej2023dyskeratosiscongenitanatural pages 1-2, niewisch2023clinicalmanifestationsof pages 1-2, franke2025diagnosisandmanagement pages 7-10)
Key causal genes & new 2024 findings	- Established genes in retrieved evidence include DKC1, TERC, TERT, TINF2, RTEL1, NOP10, NHP2, CTC1, ACD/TPP1, PARN, WRAP53/TCAB1, DCLRE1B, RPA1, NPM1, NAF1 and others; inheritance can be X-linked, autosomal dominant, or autosomal recessive. - A 2024 EMBO Molecular Medicine study reported that about 35% of clinically diagnosed cases remain genetically unresolved and expanded the allelic architecture with POLA1 (novel X-linked gene), plus additional POT1 and ZCCHC8 variants. - Functional data linked new variants to disrupted primase/CST/shelterin interactions, reduced POLA1 catalytic activity, reduced POT1 binding to telomeric ssDNA, and ZCCHC8 deficiency with pervasive transcription/inflammation. (tummala2024theevolvinggenetic pages 1-2, tummala2024theevolvinggenetic pages 3-5, niewisch2023clinicalmanifestationsof pages 1-2, rolles2024inheritedtelomerebiology pages 8-9)
Diagnostics (telomere length testing thresholds, screening yields)	- Flow-FISH lymphocyte telomere length is the current preferred functional screening test; a commonly used threshold is <1st percentile for age for strong support of TBD/DC diagnosis. - In adults, one 2023 prospective cohort used standard suspicion criteria of <10th percentile for age and an extended criterion of <6.5 kb in patients >40 years. - In 262 screened adults, shortened TL was found in 120; among standard-screened patients with NGS material, 17/76 (22.4%) had pathogenic/likely pathogenic variants and 17/76 (22.4%) had VUS; main genes were TERT, TERC, RTEL1. (rolles2024inheritedtelomerebiology pages 8-9, tometten2023identificationofadult pages 1-2, tometten2023identificationofadult pages 6-7, tometten2023identificationofadult pages 3-4, niewisch2023clinicalmanifestationsof pages 5-5)
Treatments (androgens, HSCT, organ transplant considerations)	- Androgens (especially danazol, also oxymetholone/nandrolone) can improve counts; reported hematologic response rates range about 50–100% short-term, with one study showing 11/12 patients gained telomere length (mean +386 bp) and 83% hematologic response at 24 months. - HSCT/allo-HCT is the only curative therapy for marrow failure/clonal evolution, but transplant morbidity is substantial; reduced-intensity and radiation-avoiding approaches are favored, and related donors carrying the familial defect should be avoided. - Organ transplantation (especially lung and liver) may be required for end-organ failure, but telomere disorders increase risk of hematologic and immunosuppression-related complications. (rolles2024inheritedtelomerebiology pages 12-14, ayas2026dyskeratosiscongenita pages 9-12, rolles2024inheritedtelomerebiology pages 10-12, glass2026telomerebiology pages 17-18)
Epidemiology	- DC is consistently described as ultra-rare/rare. - Retrieved prevalence estimates were approximately 1 case per 1,000,000 in one source and 1–9 per 1,000,000 in another review. - One review noted marked male predominance in historical series (male:female ~13:1), though this may reflect enrichment of X-linked DKC1 disease in some cohorts. (koldej2023dyskeratosiscongenitanatural pages 1-2, mazurek2023dyskeratosiscongenitaas pages 4-5)

Table: This table condenses the most actionable facts on dyskeratosis congenita and related telomere biology disorders from the retrieved evidence, including definition, phenotype spectrum, genetics, diagnostics, treatment, and epidemiology. It is designed to support rapid knowledge-base curation with source-linked statements.

1. Disease information

1.1 What is the disease?

DC is an inherited multisystem telomere biology disorder characterized by the classic mucocutaneous triad and a high burden of bone marrow failure (BMF), with additional complications including pulmonary and liver disease and cancer predisposition (koldej2023dyskeratosiscongenitanatural pages 1-2, rolles2024inheritedtelomerebiology pages 8-9, niewisch2023clinicalmanifestationsof pages 1-2).

1.2 Key identifiers (ontology/coding)

In the retrieved full-text evidence available for this report, specific cross-references (OMIM, Orphanet, ICD-10/ICD-11, MeSH, MONDO) were not explicitly provided, so they cannot be populated with evidence-based values here (mazurek2023dyskeratosiscongenitaas pages 4-5).

1.3 Synonyms / alternative names

Zinsser–Cole–Engman syndrome (ayas2026dyskeratosiscongenita pages 1-4, mazurek2023dyskeratosiscongenitaas pages 4-5).
DC is also referenced as the archetypal/“classic” childhood-onset form within the broader telomere biology disorders spectrum (niewisch2023clinicalmanifestationsof pages 1-2, rolles2024inheritedtelomerebiology pages 8-9).

1.4 Evidence sources and aggregation level

The information in this report is derived primarily from: - Aggregated disease-level resources and reviews (e.g., ASH Education Program review 2023; Transfusion Medicine and Hemotherapy review 2024; Nature Reviews Genetics 2023) (niewisch2023clinicalmanifestationsof pages 1-2, rolles2024inheritedtelomerebiology pages 8-9, revy2023geneticsofhuman pages 5-8). - Cohort studies/natural history studies (e.g., pediatric cohort natural history 2023; liver involvement cohort 2023; adult screening cohort 2023) (koldej2023dyskeratosiscongenitanatural pages 1-2, vittal2023progressionofliver pages 1-2, tometten2023identificationofadult pages 1-2).

2. Etiology

2.1 Disease causal factors

Primary cause: Germline pathogenic variants affecting telomere maintenance (telomerase, shelterin, CST complex/replication, telomerase RNA processing/trafficking), producing critically short telomeres and telomere dysfunction (niewisch2023clinicalmanifestationsof pages 1-2, revy2023geneticsofhuman pages 5-8, rolles2024inheritedtelomerebiology pages 8-9).

Recent genetic expansion (2024): A large 2024 DC/DC-like study identified novel pathogenic variants and newly implicated the X-linked gene POLA1; it also expanded allelic series for POT1 and ZCCHC8, with functional work implicating disrupted interactions among primase, CST, and shelterin and inflammatory signatures from ZCCHC8 deficiency (tummala2024theevolvinggenetic pages 1-2, tummala2024theevolvinggenetic pages 3-5).

Direct abstract-supported quote (2024 EMBO Mol Med): the study “identify[ied]… novel pathogenic variants… and in the novel X-linked gene, POLA1” and reported functional impacts on “protein–protein interactions with primase, CST… and shelterin” (tummala2024theevolvinggenetic pages 1-2).

2.2 Risk factors

Genetic risk: Pathogenic variants across multiple telomere genes; incomplete penetrance/variable expressivity is characteristic of TBDs, especially adult-onset “cryptic” presentations (niewisch2023clinicalmanifestationsof pages 1-2, revy2023geneticsofhuman pages 5-8).
Genetic anticipation: Adult TBD reviews emphasize generational worsening linked to inheritance of short telomere reserve (tummala2024theevolvinggenetic pages 1-2, franke2025diagnosisandmanagement pages 7-10).

Environmental/clinical risk modifiers (organ progression): In a DC/TBD liver cohort, pulmonary and/or vascular disease predicted progression to clinically significant liver disease/portal hypertension, suggesting multisystem disease burden modifies organ risk (vittal2023progressionofliver pages 1-2).

2.3 Protective factors

No specific protective genetic variants or environmental protective factors were identified in the retrieved evidence.

2.4 Gene–environment interactions

Not specifically delineated for DC in the retrieved evidence; however, clinical cohorts support that systemic comorbidities (pulmonary/vascular disease) modify progression of liver complications (vittal2023progressionofliver pages 1-2).

3. Phenotypes

3.1 Core mucocutaneous triad (suggested HPO terms)

Nail dystrophy / nail dysplasia (HPO suggestion: HP:0001597). DC childhood-onset often includes nail changes (niewisch2023clinicalmanifestationsof pages 1-2, rolles2024inheritedtelomerebiology pages 8-9).
Abnormal/reticulated skin pigmentation (HPO suggestion: HP:0000994 or related terms for skin hyperpigmentation). Frequency estimates in one review: ~90% reticulated pigmentation (mazurek2023dyskeratosiscongenitaas pages 4-5).
Oral leukoplakia (HPO suggestion: HP:0002745). Frequency estimate: ~80% (mazurek2023dyskeratosiscongenitaas pages 4-5).

Triad frequency data (review-level): reticulated pigmentation ~90%, nail dystrophy ~88%, leukoplakia ~80% (mazurek2023dyskeratosiscongenitaas pages 4-5).

3.2 Hematologic phenotypes (suggested HPO terms)

Bone marrow failure / aplastic anemia (HPO: HP:0001915 / HP:0001917). BMF is a hallmark; one chapter reports BMF in >90% by age 40 (ayas2026dyskeratosiscongenita pages 1-4).
Cytopenias: thrombocytopenia (HPO: HP:0001873), neutropenia (HPO: HP:0001875), macrocytosis (HPO: HP:0000256), pancytopenia (HPO: HP:0001876) (definitions and use in a pediatric natural history cohort) (koldej2023dyskeratosiscongenitanatural pages 2-3, koldej2023dyskeratosiscongenitanatural pages 1-2).

Pediatric natural history: in a multicenter childhood-diagnosed cohort (n=14), all had hematologic manifestations at diagnosis; 13/14 progressed to BMF at median age 8 years (range 3–18) (koldej2023dyskeratosiscongenitanatural pages 1-2).

3.3 Pulmonary phenotypes (suggested HPO terms)

Interstitial lung disease / pulmonary fibrosis (HPO: HP:0006530 for pulmonary fibrosis). One review reports interstitial lung disease in ~20% of DC patients (franke2025diagnosisandmanagement pages 7-10). A systematic review/case synthesis also states ~20% develop pulmonary fibrosis (wang2021pulmonaryfibrosisin pages 1-2).

3.4 Liver phenotypes (suggested HPO terms)

Cholestatic liver enzyme elevation / liver abnormality (HPO suggestions may include abnormal liver function tests HP:0002910).
Portal hypertension (HPO: HP:0001405).

Cohort statistics (2023 Hepatology): In a DC/TBD cohort (n=58), baseline hepatic abnormality was 72.4% and 17.2% developed clinically significant liver disease/portal hypertension over follow-up (median 6 years) (vittal2023progressionofliver pages 1-2).

3.5 Cancer predisposition

DC/TBDs are associated with increased malignancy risk; head and neck squamous cell carcinoma is highlighted as a frequent solid tumor in DC/TBD contexts, and leukemia/MDS risks are emphasized in reviews/chapters (ayas2026dyskeratosiscongenita pages 1-4, niewisch2023clinicalmanifestationsof pages 1-2).

3.6 Quality of life (QoL)

Disease morbidity is described as high and multisystemic in longitudinal pediatric follow-up, but specific validated QoL instruments (e.g., SF-36, PROMIS) and quantitative QoL scores were not available in the retrieved evidence (koldej2023dyskeratosiscongenitanatural pages 1-2).

4. Genetic / molecular information

4.1 Causal genes (selected; non-exhaustive; HGNC symbols)

Authoritative 2023–2024 reviews and studies list DC/TBD genes spanning multiple telomere modules, including: - Telomerase core: TERT, TERC (revy2023geneticsofhuman pages 5-8, rolles2024inheritedtelomerebiology pages 8-9). - H/ACA RNP and telomerase RNA stability: DKC1, NHP2, NOP10, NAF1 (revy2023geneticsofhuman pages 5-8, niewisch2023clinicalmanifestationsof pages 1-2). - Telomerase trafficking/recruitment: WRAP53/TCAB1 and related factors (niewisch2023clinicalmanifestationsof pages 1-2, rolles2024inheritedtelomerebiology pages 8-9). - Shelterin / end protection: TINF2, POT1, ACD (TPP1) (niewisch2023clinicalmanifestationsof pages 1-2, tummala2024theevolvinggenetic pages 3-5). - Replication/CST axis: CTC1 (and CST complex context), with emerging evidence that CST–Polα/primase interactions are critical (tummala2024theevolvinggenetic pages 3-5, mazurek2023dyskeratosiscongenitaas pages 1-2). - RNA processing / additional implicated loci: PARN, ZCCHC8 (tummala2024theevolvinggenetic pages 1-2, revy2023geneticsofhuman pages 5-8).

4.2 Variant classes and functional consequences

In the 2024 EMBO Molecular Medicine cohort, variant types included predominantly missense and loss-of-function categories, plus deletions/insertions (tummala2024theevolvinggenetic pages 1-2).

Mechanistic consequences from reviews include: - Impaired telomerase activity/processivity/recruitment (TERT/TERC and recruitment factors) (niewisch2023clinicalmanifestationsof pages 1-2, revy2023geneticsofhuman pages 5-8). - Reduced telomerase RNA stability/maturation (DKC1/NHP2/NOP10 axis) (revy2023geneticsofhuman pages 5-8, niewisch2023clinicalmanifestationsof pages 1-2).

4.3 Newly implicated genes/alleles (2024)

A 2024 DC/DC-like study: - Reported a novel X-linked gene POLA1 with functionally validated disease alleles and skewed X-inactivation in carrier mothers (tummala2024theevolvinggenetic pages 3-5). - Expanded the allelic series of POT1 with demonstrated reduced binding to telomeric ssDNA for pathogenic variants (tummala2024theevolvinggenetic pages 3-5). - Expanded ZCCHC8 variants associated with deficiency and inflammatory/transcriptional dysregulation signatures in blood (tummala2024theevolvinggenetic pages 1-2).

4.4 Modifier genes / polygenic background

The retrieved corpus includes evidence that incomplete penetrance/variable expressivity is common in TBDs and that broader genetic context contributes to variability; specific DC-focused protective modifiers were not identified in the retrieved evidence (niewisch2023clinicalmanifestationsof pages 1-2, revy2023geneticsofhuman pages 5-8).

5. Environmental information

No specific toxins, lifestyle exposures, or infectious triggers were identified as primary causal factors for DC in the retrieved evidence. Clinical guidance emphasizes the need to recognize DC/TBD prior to potentially harmful treatments (e.g., immunosuppression in fibrotic lung disease contexts) (wang2021pulmonaryfibrosisin pages 1-2).

6. Mechanism / pathophysiology

6.1 Current mechanistic model (upstream → downstream chain)

Upstream trigger: germline defects in telomere maintenance genes (telomerase, shelterin, CST, RNA processing/trafficking) (rolles2024inheritedtelomerebiology pages 8-9, revy2023geneticsofhuman pages 5-8).
Molecular consequence: accelerated telomere shortening and/or telomere dysfunction (very short telomeres are characteristic; diagnostic thresholds often involve <1st percentile for age) (koldej2023dyskeratosiscongenitanatural pages 1-2, rolles2024inheritedtelomerebiology pages 8-9).
Cellular consequence: activation of DNA damage responses leading to senescence and/or apoptosis, limiting replicative potential of high-turnover tissues (hematopoietic/immune/epithelial compartments) (niewisch2023clinicalmanifestationsof pages 1-2, glass2026telomerebiology pages 1-5).
Tissue consequence: stem cell depletion and organ failure phenotypes: bone marrow failure, pulmonary/liver fibrosis; genomic instability contributes to cancer predisposition (ayas2026dyskeratosiscongenita pages 1-4, vittal2023progressionofliver pages 1-2).

6.2 Pathways and processes (suggested GO terms)

Suggested GO Biological Process terms consistent with the evidence: - Telomere maintenance (GO:0000723) - DNA damage response, signal transduction by p53 class mediator (GO:0030330) - Cellular senescence (GO:0090398) - Apoptotic process (GO:0006915) - Hematopoietic stem cell differentiation / hematopoiesis (e.g., GO:0030097)

6.3 Cell types involved (suggested CL terms)

Hematopoietic stem cell (CL:0000037)
Hematopoietic progenitor cell (CL:0008001)
T cell / lymphocyte (for telomere length assays and immune involvement) (rolles2024inheritedtelomerebiology pages 8-9, niewisch2023clinicalmanifestationsof pages 5-5)
Alveolar type II cell (pulmonary fibrosis context; suggested CL:0002063) (carlier2026hematologicalcomplicationsin pages 2-3)

6.4 Mechanistic evidence from model systems

A CRISPR Ten1 knockout mouse (TEN1; CST complex) provides a DC-like in vivo model: Ten1 deficiency caused telomere shortening, short lifespan, aplastic anemia, skin hyperpigmentation, and broad organ pathology with activation of p53/p21 signaling and evidence of reduced proliferation and increased apoptosis (sanzmoreno2025lossoften1 pages 1-2, sanzmoreno2025lossoften1 pages 3-6, sanzmoreno2025lossoften1 pages 2-3). This supports a causal mechanistic route from CST dysfunction → telomere attrition → p53-mediated tissue failure.

7. Anatomical structures affected

7.1 Organ level (suggested UBERON terms)

Bone marrow (UBERON:0002371) and hematopoietic system (BMF) (ayas2026dyskeratosiscongenita pages 1-4, koldej2023dyskeratosiscongenitanatural pages 1-2).
Lung (UBERON:0002048) (pulmonary fibrosis/ILD) (franke2025diagnosisandmanagement pages 7-10, wang2021pulmonaryfibrosisin pages 1-2).
Liver (UBERON:0002107) (cholestatic abnormalities, portal hypertension) (vittal2023progressionofliver pages 1-2).
Skin (UBERON:0002097) and mucosa/oral cavity (leukoplakia) (rolles2024inheritedtelomerebiology pages 8-9, mazurek2023dyskeratosiscongenitaas pages 4-5).

7.2 Tissue and cell level

High-turnover tissues are emphasized as vulnerable to low telomere reserve, including hematopoietic and immune compartments; liver and lung involvement is prominent in DC/TBD cohorts (rolles2024inheritedtelomerebiology pages 8-9, vittal2023progressionofliver pages 1-2).

7.3 Subcellular localization (suggested GO cellular component)

Telomere (GO:0000781)
Cajal body (for WRAP53/TCAB1 biology; relevant to telomerase trafficking) (niewisch2023clinicalmanifestationsof pages 1-2)

8. Temporal development

8.1 Onset

Classic DC often manifests in childhood with mucocutaneous features, while “cryptic” TBD/DC may present in adulthood with isolated marrow, lung, liver disease, or cancer (niewisch2023clinicalmanifestationsof pages 1-2, franke2025diagnosisandmanagement pages 7-10).

8.2 Progression

Pediatric cohort: progressive accumulation of non-hematologic complications; high early hematologic morbidity with frequent progression to BMF and childhood/young-adult mortality (koldej2023dyskeratosiscongenitanatural pages 1-2).
Liver cohort: baseline liver abnormalities common; subset progresses to portal hypertension over years of follow-up (vittal2023progressionofliver pages 1-2).

9. Inheritance and population

9.1 Epidemiology

Prevalence estimate reported as ~1 per 1,000,000 in one source (koldej2023dyskeratosiscongenitanatural pages 1-2).
Another review reports 1–9 per 1,000,000 (mazurek2023dyskeratosiscongenitaas pages 4-5).

9.2 Inheritance patterns

DC/TBDs show all Mendelian modes: - X-linked recessive, autosomal dominant, and autosomal recessive inheritance (niewisch2023clinicalmanifestationsof pages 1-2, tummala2024theevolvinggenetic pages 1-2).

9.3 Demographics

A review reports strong male predominance (male:female ~13:1), likely reflecting enrichment of X-linked disease in some series; population-level sex ratio remains uncertain from the retrieved evidence (mazurek2023dyskeratosiscongenitaas pages 4-5).

Data gaps (not in retrieved evidence): incidence rates, carrier frequency, geographic/ancestry founder effects.

10. Diagnostics

10.1 Clinical criteria (core recognition)

The classic triad (nail dystrophy, skin pigmentation abnormalities, oral leukoplakia) plus hematologic and multisystem findings supports clinical suspicion (rolles2024inheritedtelomerebiology pages 8-9, niewisch2023clinicalmanifestationsof pages 1-2).

10.2 Telomere length testing (real-world implementation)

Preferred functional test: Flow-FISH telomere length measurement in leukocyte subsets; lymphocyte telomere length is described as sensitive and highly specific (rolles2024inheritedtelomerebiology pages 8-9).
Common diagnostic threshold: lymphocyte telomere length <1st percentile for age by flow-FISH strongly supports TBD/DC (rolles2024inheritedtelomerebiology pages 8-9).

Adult screening algorithm and yield (2023 prospective cohort): - Standard suspicion: <10th percentile for age; extended adult criterion: <6.5 kb in patients >40 years (tometten2023identificationofadult pages 1-2, tometten2023identificationofadult pages 3-4). - In 262 referred adults screened by flow-FISH, 120 had shortened telomeres; among standard-screened patients with NGS material, 17/76 (22.4%) had pathogenic/likely pathogenic variants and 17/76 (22.4%) had VUS (tometten2023identificationofadult pages 1-2).

10.3 Genetic testing strategy

Recent diagnostic pathways recommend: - Telomere length testing as prescreen, followed by targeted NGS panels and, if unresolved, WES/WGS focused on telomere maintenance genes (rolles2024inheritedtelomerebiology pages 10-12). - Recognition that a pathogenic variant is not found in all clinical cases (e.g., ~20% without identifiable cause in one review; ~35% unresolved in a 2024 DC cohort) (niewisch2023clinicalmanifestationsof pages 5-5, tummala2024theevolvinggenetic pages 1-2).

10.4 Differential diagnosis

Acquired aplastic anemia vs inherited marrow failure/TBD: telomere testing helps discriminate; evaluation may include Fanconi anemia chromosome breakage testing when relevant (koldej2023dyskeratosiscongenitanatural pages 2-3, NCT01659606 chunk 2).

11. Outcome / prognosis

11.1 Survival and mortality (recent cohort data)

In a Spanish pediatric DC cohort (n=14): - Median diagnosis age 8.5 years; 13 progressed to bone marrow failure at median age 8 years. - 6/14 died at median age 13 years (range 6–24) (koldej2023dyskeratosiscongenitanatural pages 1-2).

11.2 Major morbidity drivers and statistics

Bone marrow failure: reported in >90% by age 40 in a DC chapter (ayas2026dyskeratosiscongenita pages 1-4).
Liver disease: baseline abnormality 72.4%; 17.2% progressed to portal hypertension (vittal2023progressionofliver pages 1-2).
Pulmonary fibrosis/ILD: ~20% reported in reviews (franke2025diagnosisandmanagement pages 7-10, wang2021pulmonaryfibrosisin pages 1-2).

11.3 Prognostic factors

Liver progression risk enriched in recessive or TINF2-associated DC and predicted by concurrent pulmonary/vascular disease (vittal2023progressionofliver pages 1-2).
Pulmonary fibrosis systematic review suggests genotype–phenotype correlations (e.g., later ages in TERC/TERT; differences in survival by gene class), and warns against immunosuppression or lung biopsy in unrecognized DC-associated PF (wang2021pulmonaryfibrosisin pages 1-2).

12. Treatment

12.1 Pharmacotherapy — androgens

Danazol and other androgens are used as non-transplant therapies for TBD/DC-related marrow failure. - A 2024 review summarizes androgen response evidence: oxymetholone hematologic responses around 69% with frequent adverse effects; danazol with fewer side effects and reported hematologic responses (some studies ~83% at 24 months) and telomere length gains in a subset (e.g., 11/12 gained TL; mean +386 bp) (rolles2024inheritedtelomerebiology pages 12-14). - A DC chapter also reports observational hematologic response ~70% and prospective danazol trial response ~80%, while noting toxicity (liver enzyme elevation, virilization) and discontinuation risk (ayas2026dyskeratosiscongenita pages 4-7).

MAXO suggestions: androgen therapy (e.g., MAXO:0000058 pharmacotherapy; more specific term depends on MAXO mapping availability).

12.2 Hematopoietic stem cell transplantation (HSCT)

HSCT is described as the only curative therapy for DC marrow failure/clonal evolution, but outcomes are complicated by multisystem fragility (ayas2026dyskeratosiscongenita pages 9-12).

Key implementation considerations: - Avoid related donors with the same pathogenic variant when possible (risk of graft failure and adverse outcomes) (rolles2024inheritedtelomerebiology pages 10-12). - Avoid radiation in conditioning when possible because of late pulmonary toxicity and secondary malignancy concerns (ayas2026dyskeratosiscongenita pages 9-12).

ClinicalTrials.gov implementation example: A radiation- and alkylator-free HSCT regimen trial (NCT01659606) specifies conditioning with alemtuzumab and fludarabine and post-transplant immunosuppression options (mycophenolate plus cyclosporine or tacrolimus), with eligibility including DC and related syndromes (NCT01659606 chunk 2).

MAXO suggestions: hematopoietic stem cell transplantation (MAXO:0000747), reduced-intensity conditioning (MAXO term depends on available hierarchy).

12.3 Solid organ transplantation

For end-stage lung or liver disease, transplantation may be required; reviews emphasize higher complication risk and the need for careful pre-transplant TBD recognition (glass2026telomerebiology pages 17-18).

12.4 Experimental/clinical trials landscape (selected, based on retrieved trial records)

Danazol trial: NCT01441037 (“Danazol for Genetic Bone Marrow and Lung Disorders”) targets aplastic anemia/pulmonary fibrosis/liver cirrhosis phenotypes, includes pediatric patients (min age 2 years), and cites a related NEJM publication (NCT01441037 chunk 2).
HSCT trials: NCT02162420 includes transplant conditioning agents (alemtuzumab/fludarabine/cyclophosphamide/TBI, thymoglobulin) and includes “Secondary malignancies” as an outcome (NCT02162420 chunk 2).

Data gap: For some NCT records, phase/enrollment/status fields were not present in the retrieved text chunks; therefore they are not reported with evidence here (NCT01441037 chunk 2, NCT02162420 chunk 2).

13. Prevention

Primary prevention of genetic DC is not generally applicable beyond reproductive options; retrieved evidence emphasizes surveillance and avoidance of harmful interventions once disease is suspected/diagnosed. - For DC-associated pulmonary fibrosis, the systematic review warns against empiric immunosuppression and diagnostic surgical lung biopsy before excluding DC/TBD (wang2021pulmonaryfibrosisin pages 1-2).

MAXO suggestions: genetic counseling (MAXO term), surveillance program (MAXO term).

14. Other species / natural disease

No naturally occurring veterinary DC analogs were identified in the retrieved evidence.

15. Model organisms

15.1 Mammalian model (mouse)

A Ten1 (CST complex) CRISPR knockout mouse is described as a model of DC/TBD: - Phenotypes: telomere attrition, short lifespan, skin hyperpigmentation, aplastic anemia/BMF, cerebellar hypoplasia, and multi-organ pathology (sanzmoreno2025lossoften1 pages 1-2, sanzmoreno2025lossoften1 pages 2-3). - Mechanism: reduced proliferation, increased apoptosis, stem cell depletion, and activation of p53/p21 signaling (sanzmoreno2025lossoften1 pages 1-2, sanzmoreno2025lossoften1 pages 3-6).

15.2 Cellular/ex vivo models

Reviews describe use of CD34+ HSPCs and variant cell models (e.g., DKC1 variant cells), including therapeutic strategy exploration via PAPD5/7 inhibition restoring telomere length/TERC levels in specific contexts (franke2025diagnosisandmanagement pages 15-17, revy2023geneticsofhuman pages 27-30).

Notes on evidence gaps in this run

Ontology IDs (OMIM/Orphanet/MeSH/ICD/MONDO) were not directly present in retrieved full texts; they should be populated by querying OMIM/Orphanet/MONDO directly in a follow-on curation step.
QoL metrics and standardized diagnostic criteria statements (beyond telomere testing thresholds and clinical triad) were limited in retrieved evidence.

Key recent sources prioritized (2023–2024)

Tummala et al., EMBO Molecular Medicine, Aug 2024, “The evolving genetic landscape of telomere biology disorder dyskeratosis congenita.” https://doi.org/10.1038/s44321-024-00118-x (tummala2024theevolvinggenetic pages 1-2, tummala2024theevolvinggenetic pages 3-5)
Rolles et al., Transfusion Medicine and Hemotherapy, Jul 2024, “Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment.” https://doi.org/10.1159/000540109 (rolles2024inheritedtelomerebiology pages 8-9, rolles2024inheritedtelomerebiology pages 12-14)
Niewisch et al., ASH Education Program, Dec 2023, “Clinical manifestations of telomere biology disorders in adults.” https://doi.org/10.1182/hematology.2023000490 (niewisch2023clinicalmanifestationsof pages 1-2, niewisch2023clinicalmanifestationsof pages 5-5)
Tometten et al., HemaSphere, Apr 2023, adult flow-FISH screening cohort. https://doi.org/10.1097/hs9.0000000000000874 (tometten2023identificationofadult pages 1-2, tometten2023identificationofadult pages 3-4)
Vittal et al., Hepatology, May 2023, liver disease progression. https://doi.org/10.1097/hep.0000000000000461 (vittal2023progressionofliver pages 1-2)
Koldej et al., Frontiers in Pediatrics, Aug 2023, pediatric natural history cohort. https://doi.org/10.3389/fped.2023.1182476 (koldej2023dyskeratosiscongenitanatural pages 1-2)

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(rolles2024inheritedtelomerebiology pages 10-12): Benjamin Rolles, Mareike Tometten, Robert Meyer, Martin Kirschner, Fabian Beier, and Tim H. Brümmendorf. Inherited telomere biology disorders: pathophysiology, clinical presentation, diagnostics, and treatment. Transfusion Medicine and Hemotherapy, 51:292-309, Jul 2024. URL: https://doi.org/10.1159/000540109, doi:10.1159/000540109. This article has 21 citations and is from a peer-reviewed journal.
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(koldej2023dyskeratosiscongenitanatural pages 2-3): Rachel Koldej, S. Gadalla, Navarro Uria-O ﬁ cialdegui, M. L. U. FI. cialdegui, S. Navarro, L. Murillo-Sanjuán, C. Rodríguez-Vigil, M. I. Benitez-Carbante, C. Blazquez-Goñi, J. A. Salinas, and C. Díaz-de-Heredia. Dyskeratosis congenita: natural history of the disease through the study of a cohort of patients diagnosed in childhood. Frontiers in Pediatrics, Aug 2023. URL: https://doi.org/10.3389/fped.2023.1182476, doi:10.3389/fped.2023.1182476. This article has 8 citations.
(glass2026telomerebiology pages 1-5): Joshua Glass, Emma Groarke, and Neal S. Young. Telomere biology. Textbook of Bone Marrow Failure, pages 249-266, Jan 2026. URL: https://doi.org/10.1007/978-3-032-02386-5_17, doi:10.1007/978-3-032-02386-5_17. This article has 0 citations.
(carlier2026hematologicalcomplicationsin pages 2-3): François M. Carlier, Thomas Planté-Bordeneuve, Antoine Froidure, Carlos Graux, Marie-Astrid van Dievoet, Coline H. M. van Moorsel, and Thijs W. Hoffman. Hematological complications in solid organ transplant recipients with telomere biology disorders: a narrative review. Frontiers in Immunology, Jan 2026. URL: https://doi.org/10.3389/fimmu.2025.1718107, doi:10.3389/fimmu.2025.1718107. This article has 4 citations and is from a peer-reviewed journal.
(sanzmoreno2025lossoften1 pages 1-2): Adrián Sanz-Moreno, Lore Becker, Kan Xie, Patricia da Silva-Buttkus, Nathalia R. V. Dragano, Antonio Aguilar-Pimentel, Oana V. Amarie, Julia Calzada-Wack, Markus Kraiger, Stefanie Leuchtenberger, Claudia Seisenberger, Susan Marschall, Birgit Rathkolb, Enzo Scifo, Ting Liu, Anoja Thanabalasingam, Raul Sanchez-Vazquez, Paula Martinez, Maria A. Blasco, Sharon A. Savage, Helmut Fuchs, Dan Ehninger, Valérie Gailus-Durner, and Martin Hrabê de Angelis. Loss of ten1 in mice induces telomere shortening and models human dyskeratosis congenita. Science Advances, Apr 2025. URL: https://doi.org/10.1126/sciadv.adp8093, doi:10.1126/sciadv.adp8093. This article has 4 citations and is from a highest quality peer-reviewed journal.
(sanzmoreno2025lossoften1 pages 3-6): Adrián Sanz-Moreno, Lore Becker, Kan Xie, Patricia da Silva-Buttkus, Nathalia R. V. Dragano, Antonio Aguilar-Pimentel, Oana V. Amarie, Julia Calzada-Wack, Markus Kraiger, Stefanie Leuchtenberger, Claudia Seisenberger, Susan Marschall, Birgit Rathkolb, Enzo Scifo, Ting Liu, Anoja Thanabalasingam, Raul Sanchez-Vazquez, Paula Martinez, Maria A. Blasco, Sharon A. Savage, Helmut Fuchs, Dan Ehninger, Valérie Gailus-Durner, and Martin Hrabê de Angelis. Loss of ten1 in mice induces telomere shortening and models human dyskeratosis congenita. Science Advances, Apr 2025. URL: https://doi.org/10.1126/sciadv.adp8093, doi:10.1126/sciadv.adp8093. This article has 4 citations and is from a highest quality peer-reviewed journal.
(sanzmoreno2025lossoften1 pages 2-3): Adrián Sanz-Moreno, Lore Becker, Kan Xie, Patricia da Silva-Buttkus, Nathalia R. V. Dragano, Antonio Aguilar-Pimentel, Oana V. Amarie, Julia Calzada-Wack, Markus Kraiger, Stefanie Leuchtenberger, Claudia Seisenberger, Susan Marschall, Birgit Rathkolb, Enzo Scifo, Ting Liu, Anoja Thanabalasingam, Raul Sanchez-Vazquez, Paula Martinez, Maria A. Blasco, Sharon A. Savage, Helmut Fuchs, Dan Ehninger, Valérie Gailus-Durner, and Martin Hrabê de Angelis. Loss of ten1 in mice induces telomere shortening and models human dyskeratosis congenita. Science Advances, Apr 2025. URL: https://doi.org/10.1126/sciadv.adp8093, doi:10.1126/sciadv.adp8093. This article has 4 citations and is from a highest quality peer-reviewed journal.
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(NCT02162420 chunk 2): Hematopoietic Stem Cell Transplant for Dyskeratosis Congenita or Severe Aplastic Anemia. Masonic Cancer Center, University of Minnesota. 2015. ClinicalTrials.gov Identifier: NCT02162420
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(revy2023geneticsofhuman pages 27-30): Patrick Revy, Caroline Kannengiesser, and Alison A. Bertuch. Genetics of human telomere biology disorders. Nature Reviews Genetics, 24:86-108, Sep 2023. URL: https://doi.org/10.1038/s41576-022-00527-z, doi:10.1038/s41576-022-00527-z. This article has 251 citations and is from a domain leading peer-reviewed journal.

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Classifications

Inheritance

Subtypes

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Progression

Prevalence

Related Datasets

Animal Models

Source YAML

References & Deep Research

References

Deep Research

Disease Characteristics Research Template

Target Disease

Research Objectives

1. Disease Information

2. Etiology

3. Phenotypes

4. Genetic/Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

10. Diagnostics

11. Outcome/Prognosis

12. Treatment

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Citation Requirements

Output Format

Dyskeratosis Congenita (DC) — Comprehensive Disease Characteristics Report (Mendelian)

Executive summary

1. Disease information

1.1 What is the disease?

1.2 Key identifiers (ontology/coding)

1.3 Synonyms / alternative names

1.4 Evidence sources and aggregation level

2. Etiology

2.1 Disease causal factors

2.2 Risk factors

2.3 Protective factors

2.4 Gene–environment interactions

3. Phenotypes

3.1 Core mucocutaneous triad (suggested HPO terms)

3.2 Hematologic phenotypes (suggested HPO terms)

3.3 Pulmonary phenotypes (suggested HPO terms)

3.4 Liver phenotypes (suggested HPO terms)

3.5 Cancer predisposition

3.6 Quality of life (QoL)

4. Genetic / molecular information

4.1 Causal genes (selected; non-exhaustive; HGNC symbols)

4.2 Variant classes and functional consequences

4.3 Newly implicated genes/alleles (2024)

4.4 Modifier genes / polygenic background

5. Environmental information

6. Mechanism / pathophysiology

6.1 Current mechanistic model (upstream → downstream chain)

6.2 Pathways and processes (suggested GO terms)

6.3 Cell types involved (suggested CL terms)

6.4 Mechanistic evidence from model systems

7. Anatomical structures affected

7.1 Organ level (suggested UBERON terms)

7.2 Tissue and cell level

7.3 Subcellular localization (suggested GO cellular component)

8. Temporal development

8.1 Onset

8.2 Progression

9. Inheritance and population

9.1 Epidemiology

9.2 Inheritance patterns

9.3 Demographics