Multiple loci associated with canine hip dysplasia (CHD) in German shepherd dogs
Canine hip dysplasia (CHD) is the most common hereditary skeletal disorder in dogs. To identify common alleles associated with CHD, we developed 37 informative single nucleotide polymorphisms (SNPs) within 13 quantitative trait loci (QTL) previously identified for German shepherd dogs. These SNPs were genotyped in 95 German shepherd dogs affected by CHD and 95 breed, sex, and birth year-matched controls. A total of ten SNPs significant at a nominal P value of 0.05 were validated in 843 German shepherd dogs including 277 unaffected dogs and 566 CHD-affected dogs. Cases and controls were sampled from the whole German shepherd dog population in Germany in such a way that mean coancestry coefficients were below 0.1 % within cases and controls as well as among cases and controls. We identified nine SNPs significantly associated with CHD within five QTL on dog chromosomes (CFA) 3, 9, 26, 33, and 34. Genotype effects of these nine SNPs explained between 22 and 34 % of the phenotypic variance of hip dysplasia in German shepherd dogs. The strongest associated SNPs were located on CFA33 and 34 within the candidate genes PNCP, TRIO, and SLC6A3. Thus, the present study validated positional candidate genes within five QTL for CHD.