Abstract
Abstract: :
Canine breed–specific disorders provide critical models for the study and treatment of corresponding human diseases. Early retinal degeneration (erd) of Norwegian elkhounds is an autosomal recessive, early onset form of PRA. In previous studies, the erd disease locus was mapped to canine chromosome 27 between markers FH2407 (5.9 cM, Lod 2.23) and SHARP1 (0.0, Lod 27.093). Purpose: To refine the erd interval and evaluate SHARP1 as a positional candidate gene. Method: Genetic and RH mapping approaches were applied. Additional three–generation erd informative pedigrees were genotyped with newly developed gene associated polymorphic markers. Results: 30 markers were placed on the RH Map3000 of CFA27 to refine the gene and microsatellite marker in the interval. A subset of markers used for RH mapping was retrieved from the public database (http://www–recomgen.univ–rennes1.fr/doggy.html), and gene associated markers for the erd region were developed from canine BAC clones or canine sequences. Comparison of the CFA 27 RH Map3000 to the corresponding region of HSA12 demonstrated consistency in gene order (BICD1–PTHLH–ITPR–SHARP1–LRMP–SIAT8A) between two species. SHARP1 gene, which previously was mapped within the erd zero recombination region was now excluded as a positional candidate (0.014, Lod 36.075). One recombinant animal was observed between the erd locus and PTHLH. Two genes, ITPR and SSPN, were mapped inside the current erd zero recombination region (0.0, Lod 3.311). On HSA12 the interval between SHARP1 and PTHLH (the two gene–specific markers closest to erd ) covers about 2 Mb and contains 11 genes and/or predicted genes (http://genome.ucsc.edu). Conclusion: The erd region was reduced to the interval between SHARP1 and PTHLH genes. Consistent gene order was observed between the erd intervalon CFA27 and the corresponding region of HSA12. Human retina expressed genes from the region of the interest will be evaluated as positional candidates for erd. CR: N Support: MH69688–01, EY13132, EY13729, EY06855, FFB, American Border Collie Association
Keywords: retinal degenerations: hereditary • genetics • linkage analysis