The shortest known prion protein gene allele occurs in goats, has only three octapeptide repeats and is non-pathogenic

The prion protein (PrP) gene modulates the incidence and incubation periods of transmissible spongiform encephalopathies of sheep, goats, mice and man . Here, a new caprine PrP allele encoding the shortest naturally occurring PrP protein so far described is reported. This variant contains only three instead of the usual five copies of a short peptide repeat [Pro-Gln/His-Gly -Gly-Gly-(Gly)-Trp-Gly-Gln] characteristic of PrP, with an additional Trp t o Gly substitution in codon 102, Fifteen out of 111 genotyped goats carried the novel PrP allele and 14 survived without signs of disease for at least 4 years. One goat heterozygous for the polymorphism was challenged experim entally with SSBP/1-scrapie and succumbed after an unusually long incubatio n period.