Abstract
Abstract: :
Purpose:Cone-rod dystrophies (crd's) are a group of severe inherited eye diseases characterized by degeneration of cone photoreceptors followed by subsequent loss of rods. Mutations causing crd have been identified in at least seven human autosomal genes (ABCR, CRX, GUCA1A, HRG4, RetGC-1, RDS/peripherin and RHD5). A naturally occurring canine crd has been identified in the American Staffordshire Terrier. The purpose of the current study is to test for genetic association between potential candidate genes and the canine crd disease locus. Methods:To facilitate genetic investigation, a research colony was developed consisting of 58 animals with known disease status, pedigree relationship and DNA available for molecular analyses. Ten candidate genes were selected for investigation: the seven human crd genes listed above and LRAT, CRB1 and NRL. Canine microsatellites associated with each were identified, genotyped and analyzed for cosegregation with the disease. In addition, direct exon scanning was conducted where canine sequence was available. Results:Completed exon scanning revealed an absence of putative causal mutations in the coding regions of RDS/peripherin and CRX. Association analysis identified animals recombinant between canine crd and the genes CRB1, CRX, LRAT, NRL and RetGC-1. Analysis of polymorphism at other marker sets was unable to formally eliminate the associated candidate gene (ABCR, GUCA1A, HRG4 and RHD4). Conclusion:A total of six candidate genes have been eliminated as the cause of canine crd. Investigation of the remaining candidates requires analysis of additional polymorphic microsatellite markers.
Keywords: 562 retinal degenerations: hereditary • 418 gene mapping • 420 genetics