Analysis of randomly amplified polymorphic DNA (RAPD) for identifying genetic markers associated with canine hip dysplasia

Canine hip dysplasia is a heritable developmental disease resulting, in par t, from increased laxity in hip joints and is a precursor to degenerative j oint disease. Identification of genetic markers linked to joint laxity woul d foster development of more accurate diagnostic methods, facilitate identi fication of the disease gene(s), and supplement efforts to establish physic al/genetic maps of the canine genome. Work presented here describes analysi s of randomly amplified polymorphic DNA in the search for markers which cos egregate with increased joint laxity in Canis familiaris, the domestic dog. The Boykin spaniel, a highly inbred breed afflicted with an extremely high incidence of hip dysplasia, served as a model for study of canine hip dysp lasia, Only 5% of 200 random primers revealed significant polymorphisms wit hin this breed, However, polymorphisms were detected in seemingly nonpolymo rphic amplification products when digested with restriction enzymes. Restri ction digestion revealed polymorphisms in 15% of the monomorphic amplificat ion products. Among the primers that revealed polymorphisms, one primer cor rectly identified 9 of 12 dogs with regard to joint laxity. However, extens ive evaluation is required before any assertion can be made regarding linka ge of this marker to joint laxity. Of interest, another primer amplified a genomic segment unique to the canine Y chromosome.