POSTER ABSTRACTS
#22 Fifteen-year global frequency analysis of large commercial genetic testing data set: Canine prcd-PRA and Collie eye anomaly Jessica Clark1 , Heidi Anderson3, Jonas Donner3, Susan Pearce-Kelling2, Kari J Ekenstedt1 clark542@purdue.edu 1Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN, USA; 2Wisdom Panel Research Team, Wisdom Panel, Kinship, Portland, OR, USA; 3Wisdom Panel Research Team, Wisdom Panel, Kinship, Helsinki, Finland Hundreds of genetic variants associated with canine traits and disorders have been identified, with commercial tests offered. However, the geographic distributions and changes in allele and genotype frequencies over prolonged, continuous periods of time are lacking. This study utilized a large dataset of genotypes for prcd-PRA (n = 82,276 dogs) and Collie eye anomaly (CEA, n = 33,846 dogs), two autosomal recessive ophthalmic conditions, from a commercial genetic testing company (Optigen/Widom Panel, Kinship). Results span fifteen years, represent 81 countries, and include 69 breeds and breed-mixes. Dogs were genotyped for the prcd-PRA G>A missense PRCD variant or the CEA-associated NHEJ1 deletion. Between 2005 and 2019, the global trend for prcd-PRA and CEA demonstrated a significant difference in genotypic frequencies (p = 0 and p=1.775e-11, respectively), including a decline in the frequency of pcrd-PRA variant heterozygous and homozy- gous animals, and an increase in the frequency of CEA homozygous dogs, while CEA heterozygous rates remained essentially unchanged. Dogs homozygous for the prcd-PRA allele (affected, likely blind) were still observed fourteen years after test availability; reasons for this are unclear, but may represent ongoing crosses of unknown carriers. The more unexpected results for CEA likely reflect the fact that the NHEJ1 deletion segregates more strongly with choroidal dysplasia (relatively mild phenotype), than with coloboma (more severe phenotype). Breeders may be selecting away from colobomas without selecting away from the NHEJ1 deletion. Additional breed- and country-specific analyses were conducted, providing insights into the integration of genetic testing into specific breeding programs.
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