Adenomatous polyposis coli (APC), a component of DC, was first identified as a causal gene in familial adenomatous polyposis and often mutated in sporadic colorectal cancer (Kinzler et al., 1991; Kinzler and Vogelstein, 1996; Nishisho et al., 1991; Wood et al., 2007). Here, APC is linked to dyskeratosis congenita.