“…The AHQ, ARH, ARQ, and VRQ alleles are generally associated with susceptibility. The degree of, and the ranking for, susceptibility appears to be breed dependent, with the VRQ allele (when present within a breed) generally considered the most susceptible [7,8,31,44,61,64,77,79]. There is also evidence to suggest that polymorphisms at other codons within the PrP gene may modify the degree of resistance associated with the ARQ allele [82].…”