Mutations of the dyskerin-encoding gene DKC1 causes X-linked recessive dyskeratosis congenita (DKC), a rare progressive congenital disorder that mostly affects highly regenerative tissues, such as the skin and bone marrow (Heiss et al., 1998; Mochizuki et al., 2004). The gene discussed is DKC1; the disease is dyskeratosis congenita.