Frequencies of PrP codons 222K, 146S and 146D contributing to resistance to classical scrapie.

In several countries (Italy incl. Sicily and Sardinia, Greece, United Kingdom, France, Spain, Germany) have been performed more extended searches for existence of live PrP resistance polymorphism carriers under goats. The PrP-alleles of interest were especially Q222K, N146D and N146S, shortly indicated as 222K, 146S and 146D. 

Of these three, 222K is present in most breeds but not all. Where it occurs it has a frequency varying per breed and per region between 2-18%. The Toggenburger breed in the Netherlands showed a 30% frequency, the highest ever reported. Breeds that are most present in the European production population are the Alpine and Saanen breed; these show 222K allele frequencies of about respectively 8 and 5%. Such low levels are high enough to start a careful breeding program.

The 146S and 146D alleles occur in high frequencies on Cyprus and in lower levels on some islands of Greece, due to the presence of the Damascus breed (originating from Asia Minor). The 146S allele also was found under Boar goats and other meat producing breeds on the main land of Europe.

Other PrP codon variants might also contribute to resistance but either are only contributing to a limited level of resistance or are too unfrequent to be used at this stage for breeding purposes. 

These results have been obtained in the GOAT-TSE-FREE project supported within European program EMIDA/ERANET and carried out by 8 partners in seven EU countries: France, Greece, Germany, Italy, Spain, The Netherlands, United Kingdom, as well as on Cyprus under a specific DG Santé directed program (logo).