A teenage boy develops reticulate hyperpigmentation of the neck, nail dystrophy, and white plaques on the buccal mucosa. Bone marrow examination at age 20 reveals aplastic anaemia. The gene classically mutated in the X-linked form encodes:

• A Telomerase reverse transcriptase
• B ATM kinase
• C Dyskerin ✓
• D RecQ helicase

Explanation

Dyskeratosis congenita shows the mucocutaneous triad of reticulate skin pigmentation, nail dystrophy, and oral leukoplakia, followed by bone marrow failure; the X-linked form arises from DKC1 mutation encoding dyskerin, a protein needed for telomere maintenance. ATM causes ataxia telangiectasia, RecQ helicases cause Bloom and Rothmund-Thomson syndromes, and TERT mutations account for autosomal dominant forms only.

Reference: Fitzpatrick's Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.