Among the residues of this region identical in human and D discoideum DKC1 proteins are two amino acids mutated in DC patients: Isoleucin 38 (Ile38) and Threonin 49 (Thr49) in humans that correspond to Ile23 and Thr33, respectively, in D. discoideum. The gene discussed is DKC1; the disease is dyskeratosis congenita.