Dyskeratosis congenita
DC; Zinsser-Cole-Engman syndrome; "telomere biology disorder" / "short telomere syndrome" — broader umbrella now used to encompass DC and related disorders (Hoyeraal-Hreidarsson syndrome, Revesz syndrome, Coats plus)
Dyskeratosis congenita is a rare inherited telomere maintenance disorder caused by germline mutations affecting telomere maintenance proteins — most commonly DKC1 (X-linked recessive), TERT, TERC, TINF2, RTEL1 and others — leading to abnormally short telomeres and impaired tissue renewal in highly proliferative tissues. The classical mucocutaneous triad — nail dystrophy, oral leukoplakia and reticulated skin hyperpigmentation — develops progressively from late childhood. Patients suffer life-threatening bone-marrow failure from the second decade, pulmonary fibrosis and liver disease, and substantially elevated lifetime risks of head-and-neck and anogenital squamous cell carcinoma, leukaemia and myelodysplastic syndrome. Allogeneic haematopoietic stem-cell transplantation cures the marrow component but, like Fanconi anaemia, does not reduce — and may increase — solid tumour risk. The dermatologist often makes the initial diagnosis through the mucocutaneous triad and is critical for lifelong cancer surveillance.
Genetics
- Germline mutations in genes encoding telomere maintenance proteins:
- DKC1 (X-linked recessive; ~30%) — encodes dyskerin.
- TERT (autosomal dominant or recessive) — telomerase reverse transcriptase.
- TERC (autosomal dominant) — telomerase RNA component.
- TINF2 (autosomal dominant; ~12%) — shelterin complex.
- RTEL1, NHP2, NOP10, WRAP53, CTC1, ACD, PARN — additional autosomal recessive / dominant genes.
- Result — abnormally short telomeres → premature replicative senescence in highly proliferative tissues (marrow, mucosa, gut).
- Confirmed by flow-FISH demonstration of abnormally short telomeres (<1st centile for age) plus germline sequencing.
- Clinical severity correlates with degree of telomere shortening; severe early-onset variants (Hoyeraal-Hreidarsson syndrome, Revesz syndrome) are clinically distinct.
Mucocutaneous triad & systemic features
- Nail dystrophy (~90% of patients) — progressive longitudinal ridging, splitting, atrophy of all nails from late childhood.
- Oral leukoplakia (~80%) — white patches on tongue, buccal mucosa, palate; pre-malignant.
- Reticulated skin hyperpigmentation (~90%) — net-like grey-brown pigmentation over the upper trunk, neck and face.
- Bone-marrow failure — pancytopenia from second decade.
- Pulmonary fibrosis — adults; major cause of mortality.
- Liver disease — cirrhosis, vascular liver disease (nodular regenerative hyperplasia).
- Premature greying / hair loss; epiphora (lacrimal duct obstruction); dental abnormalities; oesophageal strictures; hypogonadism; learning difficulties.
Cancer risk
- Head-and-neck squamous cell carcinoma — ~500-fold relative risk; cumulative risk >30% by age 50; tongue and oral cavity most common.
- Anogenital squamous cell carcinoma — ~100-fold relative risk; vulva, anus, perianal skin.
- Cutaneous squamous cell carcinoma — ~70-fold relative risk.
- Acute myeloid leukaemia / myelodysplastic syndrome — major risk; develops from underlying marrow failure.
- Hodgkin lymphoma, non-Hodgkin lymphoma, oesophageal SCC, hepatocellular carcinoma — increased risk.
- Risk further amplified by post-allogeneic-transplant chronic GvHD and conditioning chemoradiotherapy.
Surveillance
- Multidisciplinary care — paediatric / adult haematology, dermatology, ENT / oral medicine, gynaecology, respiratory medicine, hepatology, clinical genetics.
- Annual oral examination from age 10 by ENT / oral medicine; biopsy any leukoplakia / change.
- Annual gynaecological examination from late adolescence; HPV vaccination if not already received.
- Annual full skin examination from late childhood.
- Annual upper-GI endoscopy in adults if symptoms or risk factors.
- Marrow surveillance and management of cytopenias / leukaemia by haematology.
- Strict avoidance of tobacco and alcohol.
- Photoprotection — daily SPF 50+, sun-protective clothing.
- Pulmonary function and CT chest surveillance for fibrosis.
- Liver function surveillance.
- HPV vaccination for all DC patients.
Management of cancers
- Wide local excision is the cornerstone of mucocutaneous SCC management.
- Markedly enhanced normal-tissue toxicity from radiotherapy and chemotherapy related to defective telomere maintenance and limited proliferative reserve — radiotherapy and chemotherapy must be used cautiously, with reduced doses and specialist input.
- Anti-PD-1 immunotherapy (cemiplimab, pembrolizumab) — emerging option for advanced disease.
- Allogeneic haematopoietic stem-cell transplantation cures the marrow disease but does not reduce post-transplant solid tumour risk; uses reduced-intensity conditioning to mitigate toxicity in DC patients.
- Genetic counselling and cascade testing of relatives.
References
- Savage SA, Cook EF (eds). Dyskeratosis congenita and telomere biology disorders — diagnosis and management guidelines. 4th edition; 2022.
- Alter BP et al. Cancer in dyskeratosis congenita. Blood; 2009.
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