[Genetic analysis of a patient with dyskeratosis congenita].

Dyskeratosis congenita (DKC) is a rare inherited disease characterized by reticulated pigmentation of the skin, nail dystrophy and oral leukoplakia. More than 90% of DKC cases are inherited as an X-linked recessive trait. Half the patients develop progressive pancytopenia by the age of 11 yr, and this is the leading cause of death. We experienced a 11-year-old boy with the above symptomatic triad of DKC, complicated by progressive pancytopenia as well as cerebellar ataxia. Genetic analysis of mRNA from his cultured peripheral lymphocytes revealed a missense mutation resulting in substitution of 1,150 C with T in the DKC1 gene. This is identical to the mutation reported by Knight et al. to be prevalent in X-linked cases of DKC (11 out of 21 patients). Existence of the identical mutation in Japan suggests that this mutation has been selected on the basis of not only the DNA structural sequence of dyskerin, but also its biological function. We report the detailed clinical course of this Japanese DKC patient with a mutation in the DKC1 gene, and describe the results of genetic analysis.