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Title: Genome-wide association identifies genomic regions associated with entropion in domestic sheep

item Mousel, Michelle
item White, Stephen
item Reynolds, James
item Knowles Jr, Donald

Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: 4/21/2014
Publication Date: 8/17/2014
Citation: Mousel, M.R., White, S.N., Reynolds, J.O., Knowles Jr, D.P. 2014. Genome-wide association identifies genomic regions associated with entropion in domestic sheep. WCGALP,Vancouver Canada.

Interpretive Summary: Modern genetic technologies can be used to improve the health and well-being of lambs. Improvement of lamb health will increase the value of lambs and the efficiency of producing human foods. Thus, genetics studies are underway at the USDA, Agricultural Research Service, and Animal Research Unit to identify genes associated with health traits. Recent results from these studies indicate that more than one gene is associated with entropion, a disorder in which the eyelid rolls inward causing the eyelash to irritate the eye. Sheep producers can use this information to make significant improvements in the health of sheep and thus the efficiency of producing human foods.

Technical Abstract: Entropion is an inversion of the eyelid allowing direct contact between the eyelashes and cornea, potentially causing blindness if not treated. In domestic sheep, entropion has a variable frequency (0-80%) worldwide and is heritable (heritability 0.08-0.21). Identification of genes associated with entropion could facilitate development of genetic markers to select against entropion. Therefore, a genome-wide association scan was conducted with 998 Columbia, Polypay, and Rambouillet sheep genotyped using the Illumina OvineSNP50 BeadChip. Entropion status was recorded within 48 hours of birth and overall prevalence was 5.6%. Data was analyzed using logistic regression models in PLINK v1.06 that accounted for breed, PPC clusters, and SNP minor allele. One genome-wide significant (P<1x10-8) SNP was identified on chromosome 6 and five SNP were genome-wide suggestive (P<1x10-6) on chromosomes 1, 2, 13 and 16. We are evaluating these regions to identify the underlying causal mutations.