We found that the ratios of pyroglutamylated PrPSc fragments were different in sheep of different breeds and geographical origin, and our expanded ovine PrPSc assay was able to determine the ratio and allotypes of PrP accumulating in diseased brain of PrP heterozygous sheep; it also revealed significant differences between N-terminal amino acid profiles (N-TAAPs) in other types of ovine prion disease, CH1641 scrapie and ovine BSE. The gene discussed is PRNP; the disease is prion disease.