Polycystic Kidney Disease (PKD) is a well documented abnormality in domestic cats. Cystic kidneys can sporadically occur in any population of cats. PKD is not a new disease and has been reported in the literature for over 30 years. The heritable form of PKD1 may not have initially occurred in Persians as a new mutation, but perhaps in random bred cats. Unfortunately, PKD1 does not have a strong clinical presentation. The presentation of PKD1 is similar to one of the most common causes of death for any cat, renal failure. Thus, PKD1 has gone unnoticed for many years and has spread throughout the Persian breed. Any breed that has used Persians in their foundation or propagation should have concerns for PKD1.
In Persians, the condition has been shown to be inherited as a single autosomal dominant gene. It is estimated over 37% of Persians have PKD1, a breed that accounts for nearly 80% of the cat fancy. Many lines and catteries have been able to greatly reduce this frequency by using ultrasound screening methods and improved breeding practices.
Detailed PKD1 InformationGenetics and Inheritance
Early onset, bilateral presentation (both kidneys), and multiple cysts are all traits of the heritable form of the disease. The kidney cysts for PKD1 present early, often before 12 months of age. Renal failure, however, usually occurs at a later age. Thus, PKD1 is considered a late onset renal disease. In the fancy cat breeds, PKD1 is inherited as an autosomal dominant condition. This implies that one copy of the gene is required to produce PKD1. Generally, 50% of PKD1 positive cats' offspring will inherit PKD1. A positive cat could potentially be homozygous for PKD1 and all offspring produced would have PKD1. It is suspected that cats that are homozygous for PKD1 are not abundant and the homozygote form could be lethal in utero or severely present at a very early age. Further research is required to prove the effects of the homozygote condition.Which Cats Should Be Tested for PKD1?
Currently we recommend the PKD1 test for British Shorthair, Persians, Exotics, Scottish Fold, Burmillas, Himalayans and Persian out-crosses only.
PKD1 is most common in the Persians and breeds that are related to Persians or have used them in breeding programs. Examples include: Exotics, Himalayans, American Shorthairs and Scottish Folds. Other breeds may have inherited PKD1 from an accidental use of either a purebred or random bred cat that had the heritable form of PKD1.
Sections reprinted with permission of: Leslie A. Lyons Ph.D., Assistant Professor, Department of Population Health and Reproduction, University of California, Davis.