In recent studies, association studies of prion protein family genes have received attention as a novel view for prion diseases: prion-like protein gene (PRND), prion-related protein gene (PRNT), and shadow of prion protein gene (SPRN) which encode Doppel, Prt, and Shadoo, respectively [3,18,22,23]. The gene discussed is PRND; the disease is prion disease.