Polycystic Kidney Disease – Siberian Research

Polycystic Kidney Disease is a genetic mutation causing benign cysts in the kidneys and other organs. The disease progresses at very different rates, but can cause very early death. PKD has long been considered to be a Persian disease, but accidental and deliberate outcrosses spread PKD to other breeds. Breeders in Russia, Germany, and the USA used Persians in an effort to increase coat density and round the face. These outcrosses have brought several genetic Persian diseases into the breed, – including Persian Polycystic Kidney Disease (PKD1).

In October of 2006, SRI submitted a pedigree analysis of Siberians affected by PKD to Dr Leslie Lyons (UC Davis Feline genetics at that time). Roughly 35 cases of PKD have been reported directly to Siberian Research with the majority of participating catteries requesting confidentiality. Extrapolation by a population geneticist estimated that PKD affected between 500 and 1000 Siberians worldwide in 2005.

There are several different genetic tests for PKD, but DNA analysis confirms that most samples submitted by Siberian Research were positive for the Persian Mutation. In 2005, a few cases confirmed by sonogram were negative using the UC Davis test, but positive using an Italian Persian DNA test. A revised version of UC Davis test was being evaluated. Regardless, DNA tests are the simplest way to quickly reduce Siberian PKD.

Traditional PKD is a dominant gene, and since the disease always shows in affected offspring it is fairly simple to track the lineages. Pedigree analysis have revealed five potential distinct entry points of PKD in the Siberian breed, though cases from new Russian lines are still being reported.

1) The vast majority of reported PKD cases come from the mating of Kuzya and Lemurotchka. Same of 2005, Germany had the highest concentrations of this line, but these lines were also widely dispersed in the U.S. and other countries. Pedigree analysis shows half of the offspring from Kuzya were positive PKD.

2) Pyramid Kazan of Croshka and his daughter died very young of PKD, with confirmation by necropsy. Samskatts Texas Star also tested positive, and is from the same ancestry. The focal point for these pedigrees is Gesha Olenya Krasa / Dolka Olenya Krasa / Dima El Magrib. This line can be tested using the standard PKD gene test.

3) Gregory’s Siberian Petra Jamesova and Gregory’s Siberian Penelope Jamesova. Associazione del Gatto Siberiano has reported two siblings with PKD. Both cats have had extensive workups, and the diagnosis was confirmed by DNA. In 2005, DNA tests by UC Davis were negative. Dr. Leslie Lyons (Feline geneticist for UC Davis at that time) confirmed there are variations between DNA tests at different laboratories that could account for this result. We recommend this line is also tested by ultrasound as well as DNA.

4) Uliana Golden Assolada (pedigree linked here) was diagnosed with PKD by ultrasound, but was not tested by DNA. No additional cases were reported from this line.

5) Two imported siblings in the UK were diagnosed by genetic testing and returned to the breeder in Russia. The breeder declined to release the names or pedigree. No additional cases have been reported on that line, but the majority of cases go unreported. Both kittens tested positive for Persian PKD, indicating a new Persian outcross.

By breeding age, PKD can usually be seen by ultrasound (some cysts may be too small to show clearly). The affected parents will always show positive DNA results. Siberian Research documented that the Persian gene test is always effective on the Kuzya X Lemurotchka line. We suggest kitten buyers and catteries are cautious when purchasing kittens descended from any of the matings listed above.

we recommend reviewing pedigrees before purchasing breeding cats. Pedigree depth on the Kuzya / Lemurotschka matings now exceeds eight generations. Fill out your pedigree using PawPeds, and expand to 8 generations. PawPeds is currently the leading source of pedigree data – please remember to submit your pedigrees to them. Of note, In one well documented case, theccc Russian pedigree was “shortened” by two generations to remove the Kuzya/Lemurotschka mating. We documented this type of pedigree fraud multiple times in Russian and older German pedigrees.

Resources for research and testing of PKD are listed below. Breeders are strongly encouraged to review lines known to be impacted with PKD prior to purchase or breeding kittens. Genetic Screening for Feline Persian Polycystic Kidney Disease

Autosomal Dominant Polycystic Kidney Disease in Persian Cats
Definitions, diagnosis, treatment, and offspring probabilities (by Biller et al).

Feline Polycystic Kidney Disease Mutation Identified in PKD1
Journal of the American Society of Nephrology (by Lyons et al).
http://jasn.asnjournals.org/cgi/content/full/15/10/2548