DKC1 and dyskeratosis congenita: At present, approximately 50% of DC patients have an identified mutation in one of eight genes involved in the telomerase complex [DKC1, TERC (encoding hTR), TERT, NHP2, NOP10], the Cajal body localizing co-factor TCAB1 [10], [11], the relatively unknown gene C16orf57 [12], or the shelterin complex (TINF2) [13].