Linkage analysis of two murine polycystic kidney disease genes, pcy and cpk

Two murine models of polycystic kidney disease (PKD) in humans are currently available: the infant-type cpk in mice and the adult-type pcy mutation in mice. Our linkage analysis was to determine whether these genes are allelic forms of the same gene, or infant-type and adult-type PKD resulting from homozygous and heterozygous mutation, as in the rat Cy gene. We found that the pcy gene in the mice was linked with the d gene on chromosome 9, but the cpk gene was not. A segregation test indicated that the two genes are inherited independently. This indicates that the cpk and pcy genes are not alleles and that the genetic mechanism of PKD pathogenesis in the mouse is different from that in the Cy rat.