PRNP and scrapie: In addition, the PRNP polymorphisms at codons 21, 23, 37, 49, 102, 110, 127, 133, 137, 139, 142, 142, 143, 146, 146, 151, 154, 168, 173, 211, 218, 220, and 240 have been evaluated for scrapie genetic resistance in goats [15,16,17,22,26,30,31,32,33].