We found 3 novel missense variants in the open reading frame of the prion protein (PrP) gene. The codon 105 point mutation (proline to leucine) was found on a codon 129 (Valine) PrP allele in 4 patients from 3 different Japanese families with Gerstmann-Sträussler syndrome. The codon 180 variant PrP (valine to isoleucine) was found in Creutzfeldt-Jakob disease (CJD) patients with a similar clinical course to that of codon 178 mutation. The codon 232 variant PrP (methionine to arginine) was documented in the CJD patients with typical clinical and pathological findings. These variant PrP molecules were not detected in 200 normal Japanese PrP alleles. PrP has a large repertoire of variant forms, and each primary structure of PrP corresponds to the distinct phenotype of prion diseases.