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

Abstract Text: 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.

Keywords: Domestic sheep, Entropion, Genome-wide association study