Do PKD Positive Homozygotes Exist?
To date, there is no proof whether PKD positive homozygotes (PP) exist or not. We may not know the answer to this question until a DNA test is available and that test has been used on a significant number of PKD positive cats. However, Dr. DiBartola, Professor of Veterinary Clinical Sciences at The Ohio State University says: “In all likelihood, the homozygous state (PP) for ADPKD probably is not viable. No human homozygotes have ever been detected and recent work using so-called “knockout” mouse models of PKD1 (Dr Zhou at Harvard) and PKD2 (Dr Somlo at Albert Einstein in NY) (in which the researchers genetically target and inactivate a gene) has shown that mouse embryos homozygous for mutations in PKD1 or PKD2 have severe abnormalities in kidneys and other organs with branching tubular epithelial structures (e.g. biliary tree, pancreas) that preclude survival. Thus it is VERY UNLIKELY that homozygotes live ex utero.” Stephen P. DiBartola, DVM, DACVIM (from a private e-mail 11/2/98) An
