A point mutation was introduced into exon 3 that altered the sequence encoding amino acid 101 from one that encodes a proline to one that encodes a leucine P101L). This residue is equivalent to amino acid 102 in humans, and the mutation is associated with Gerstmann-Straussler syndrome. A full length mRNA is expressed from this allele at similar levels to wild-type. Western blot analysis from brain homogenates detected a slight reduction in the amount of total protein in homozygous mutant mice as compared to wild type.