Maura Mack
,
University of California-Davis, Davis, CA
SK Beeson
,
University of Minnesota, St. Paul, MN
Heather Kaese
,
Eye Care for Animals, Lee’s Summit, MO
James R Mickelson
,
University of Minnesota, St. Paul, MN
Mark Rutherford
,
University of Minnesota, St. Paul, MN
Lynne Sandmeyer
,
University of Saskatchewan, Saskatoon, SK, Canada
Bianca Bauer
,
University of Saskatchewan, Saskatoon, SK, Canada
Mary Lassaline
,
University of California-Davis, Davis, CA
Ann Dwyer
,
Genesee Valley Equine Clinic, Scottsville, NY
Molly E McCue
,
University of Minnesota, St. Paul, MN
Rebecca R. Bellone
,
University of California-Davis, Davis, CA
Equine recurrent uveitis (ERU), the leading cause of blindness in horses, is characterized by bouts of inflammation in the ocular uveal tract. Appaloosas are more likely to develop ERU and go blind than any other breed, suggesting that genetics plays a vital role. Appaloosas are best known for their white spotting patterns, caused by the leopard complex spotting locus (
LP). Markers linked to
LP on ECA1 and MHC on ECA20 were previously associated with increased risk for ERU. The goals of this study are to determine the extent to which genetics contributes to this disease and further investigate the previously associated loci while identifying additional loci.
A genome wide association study was performed using the Illumina Equine SNP70 BeadChip in 93 horses. To correct for relatedness, heritability estimates and association testing were performed using several additive mixed model approaches. Heritability of ERU was high, h2= 0.7-0.99 (p= 3.47X10-5). While not reaching genome-wide significance, three mixed models identified loci on ECA1, ECA12, and ECA29 for further analysis (p=2.28X10-5, p=3.17X10-5, p=4.66X10-5 respectively). Using LP as a covariate provided further support for the loci on ECA12 and ECA29.
Overall, the results of this analysis suggest that ERU is highly heritable, LP has a direct effect on ERU risk, and other loci are involved. The variance detected in our heritability estimates suggests that estimates may be biased upward due to the relatively small sample size. Testing additional samples and markers should give a more refined estimate and greater support for loci warranting further investigation.
