Update from the middle of year 2 of research underway by Dr. Iivanainen of University of Helsinki to hopefully lead to a genetic test to aid breeders in controlling hip dysplasia.
The overall objective of our study is to perform a genome wide association study (GWAS) of canine hip dysplasia (CHD) in German Shepherds using a large sample cohort (200 cases and 200 controls). CHD is a common problem in many breeds. The dysplasia phenotype is graded from radiographs. In this study, we use the standards of Fédération Cynologique Internationale (FCI) ranging from A (healthy) to E (severely dysplastic). Each hip joint is graded individually. As the disease progresses also the risk for hip joint arthrosis – a painful and incurable condition – increases. The identification of genetic risk factors would enable the development of genetic tests to aid the breeders in controlling the disease. Four hundred animals consisting of carefully matched pairs of healthy and affected individuals should provide enough power for the association study to uncover the major genetic risk factors for this degenerative disease.
Since last report at the end of 2014, we have not performed larger genome-wide association studies but have instead concentrated our efforts on expanding the study cohort. The preliminary GWAS during 2014 was done using the cohort of 286 genotyped individuals and uncovered a promising association signal from one canine chromosome. This chromosomal region is currently under further analysis.
At present, we have collected a study cohort of 1141 dogs including 411 cases and 730 controls. 171 cases (with FCI-graded “D” or “E” hip joints) and 171 controls (with bilateral “A” hip joints) have been extracted from the study cohort. This subset is balanced with regards to working, show or mixed line subpopulations. From the balanced cohort, we have thus far genotyped 143 cases and 143 matched controls (see the figure below).
Figure. The present size of the total sample cohort (with C-, D-, or E-graded cases and Agraded controls), balanced cohort (with C-, D- or E-graded cases and individually matched Agraded controls), and the number of determined genotypes in relation to the overall objective of genome-wide association study using 200 dysplastic and 200 control dogs.