Closely Linked Polymorphic Markers for Determining the Autosomal Dominant Allele (Cy) in Rat Polycystic Kidney Disease

The Han:SPRD strain is an SD-background strainknown to be a model of polycystic kidney disease (PKD)expressed through an autosomal dominant gene (Cy).However, different genotypes of this strain cannot be identified in the neonatal period. First, toestablish an accurate method of determining thegenotypes (Cy/Cy, Cy/+, +/+) which cause differentdisease progressions, we used polymorphic markers on rat chromosome 5. PCR products of tissue DNAtemplated with D5Rat9 showed distinct patterns onelectrophoresis indicating three genotypes. Second, todetermine whether the same locus plays a major role inexpressing PKD, we performed linkage analyses in a BN X(BN X Han:SPRD)F₁] backcross. Cy/Cy and Cy/+also caused PKD in a BN background. In this backcross,we discovered that D5Rat11 is located closer to the Cy locus than D5Mgh10, which is regardedas one of the closest loci. We conclude that D5Rat9 andD5Rat11 are useful markers for determining the presenceof the Cy allele, which is regarded as the gene responsible for PKD.