Goat Scrapie Susceptibility (SCRAPIE)
Scrapie, Prion Disease
Goat Scrapie Susceptibility (SCRAPIE) testing is an important tool for reducing this highly infectious disease in goats. Scrapie is an infectious and fatal neurodegenerative disease caused by an infectious protein known as a “Prion”. Prions can cause disease in many species including humans, cattle, sheep, and goats. The disease progresses due to the spread of an improperly folded protein that not only leads to disease symptoms but can go on to misfold other normal proteins that leads to disease progression and eventual death. There is no treatment for Scrapie and all affected animals need to be euthanized to prevent further spread of the disease. Natural mutations have been identified in the Prion protein in goats that confers resistance to Scrapie that include the S146, K222, and D146 mutations. Each mutation is named for the amino acid that is changed in the protein that ultimately leads to disease resistance. Test results can be used to increase the frequency of these beneficial mutations and ultimately control Scrapie disease in goat herds. This test if applicable to all goat breeds both within and outside the United States. Additional information can be found at:
https://www.aphis.usda.gov/sites/default/files/scrapie-genotyping-brief.pdf
Reading Your Results
Test result explanation is based on the combined results for S146/D146 and K222 tests. Associated risk levels for different result combinations can be found in the following table:
| S146/D146 | K222 | Associated Risk | Test Result Explanation |
| NN/NN | Susceptible | Genotype NN/NN and QQ. No resistance to classical scrapie. | |
| NN/NN | QK | Resistant | Genotype NN/NN and QK. One copy of protective variant K222, increased resistance to classical scrapie. |
| NN/NN | KK | Resistant | Genotype NN/NN and KK. Two copies of protective variant K222, increased resistance to classical scrapie. |
| NS/ND | Resistant | Genotype NS/ND and QQ. One copy of protective variant S146/D146, increased resistance to classical scrapie. | |
| NS/ND | QK | Resistant | Genotype NS/ND and QK. One copy of each of S146/D146 and K222 protective variants, increased resistance to classical scrapie. |
| SS/DD | Resistant | Genotype SS/DD and QQ. Two copies of protective variant S146/D146, increased resistance to classical scrapie. |
Additional Details
Inheritances
Autosomal Dominant
Affected gene
PRNP
Chromosome
Ch. 13
Mutation
N146S, Q222K, N146D
Publication:
Papasavva-Stylianou, P., Kleanthous, M., Toumazos, P., Mavrikiou, P., & Loucaides, P. (2007). Novel polymorphisms at codons 146 and 151 in the prion protein gene of Cyprus goats, and their association with natural scrapie. Veterinary journal (London, England : 1997), 173(2), 459–462. [PubMed: 16314132].
White, S., Herrmann-Hoesing, L., O’Rourke, K., Waldron, D., Rowe, J., & Alverson, J. (2008). Prion gene (PRNP) haplotype variation in United States goat breeds. Genetics Selection Evolution, 40(5), 553-561. [PubMed: 18694550].
White, S.N., Reynolds, J.O., Waldron, D.F., Schneider, D.A., & O’Rourke, K.I. (2012). Extended scrapie incubation time in goats singly heterozygous for PRNP S146 or K222. Gene, 501(1), 49-51. [PubMed: 22516690].
Cinar, M.U., Schneider, D.A., Waldron, D.F., O’Rourke, K.I., & White, S.N. (2018). Goats singly heterozygous for PRNP S146 or K222 orally inoculated with classical scrapie at birth show no disease at ages well beyond 6 years. The Veterinary Journal, 233, 19-24. [PubMed: 29486874].
