Prion protein genotype survey confirms low frequency of scrapie-resistant K222 allele in British goat herds

Scrapie in goats is a transmissible, fatal prion disease which is endemic in the British goat population. The recent success in defining caprine PRNP gene variants which provide resistance to experimental and natural classical scrapie has prompted us to conduct a survey of PRNP genotypes in ten goat breeds and 52 herds to find goats with the resistant K222 allele. We report here the frequencies in 1236 tested animals of the resistance-associated K222 and several other alleles by breed and herd. Eight animals were found to be heterozygous QK222 goats (0.64% genotype frequency, 95% confidence interval: 0.28-1.27%) but no homozygous KK222 goats were detected. The K222 allele was found in Saanen, Toggenburg and Anglo-Nubian goats. The fact that only a few goats with the K222 allele have been identified does not preclude the possibility to design and implement successful breeding programmes at national level.