The Feline PKD mutation work has been published in the Journal of the American Society of Nephrology 15: 2548-2555.

Attention Breeders: Ultrasound PKD clinics for disease severity coming soon!

Acknowledgements

The genetic mutation that causes PKD in Persian cats has been identified by the feline genetics laboratory of Dr. Leslie Lyons at the UC Davis School of Veterinary Medicine. Several funding agencies have supported the research of the Lyons' laboratory, including, the Winn Feline Foundation, the Waltham Foundation, the UC Davis Center for Companion Animal Health and the NIH - National Center for Research Resources. The project's success was highly dependent on the continued collaborations with radiologist David S. Biller, DVM, Kansas State University, College of Veterinary Medicine. Ultrasound assistance was provided by radiologist Eric Hergessell, DVM, UC Davis, School of Veterinary Medicine, Department of Radiological & Surgical Sciences. A team effort from the Lyons' laboratory ensured the projects success, which included the research efforts provided by Heather R. Roberts, PhD., Amy E. Young, MS., Monika J. Lipinski, HyungChul Rah, and Robert A. Grahn, PhD. The mutation was identified by Carolyn A. Erdman, MS. Sequencing of the full-length genomic clone of feline PKD1 was provided by the Oklahoma Sequencing Center, Bruce A. Roe, PhD., University of Oklahoma.

Most importantly, we greatly appreciate the cat breeders who participated in our PKD ultrasound screening clinics. The project had rapid success due to the overwhelming enthusiasm of the Persian breeders and their continued cooperation.

Genetics

The mutation that causes Persian PKD is located in the gene called PKD1. This gene produces a protein called "polycystin". Over 85% of human PKD is causes by mutations in the human version of the same gene. In the Persian cat, a simple point mutation in exon 29 causes an amino acid change in the protein of affected cats, preventing the production of approximately 33% of the normal protein. No cats have yet been identified that are homozygous (have 2 copies) of the PKD mutation. It is suspected that these kittens die in utero. The identification of the mutation does NOT determine severity of the disease, thus, further ultrasound could assist with proper breeding decisions. Please refer to the discussion under Cattery Management as it is important to maintain the different lines of Persian cats and to SLOWLY eradicate the disease.

Breeds with PKD

PKD is most common in the Persian breed and breeds that are related to Persians or have used them in their breeding programs. Examples include: Exotics, Himylayans, American Shorthairs and Scottish Folds. Others breeds could have accidently picked-up PKD from an accidental use of either a purebred or random bred, that had the heritable form of PKD. Rcently, we have discovered Ragdolls that are positive for PKD. We have not found PKD in Norwegian Forest Cats, Chartreux, American Wirehairs, Maine Coons and Birmans, but we have screened a limited number of cats from only a single or few catteries. This test must be VALIDATED in other breeds before it is used for screening in non-Persian related cats. Currently we recommend the PKD test for Persians, Exotics and Himylayans only. Other cat breeds could be screened if it is known that they bred with Persians.  We need to validate the test in other breeds, thus, if you have cats with confirmed positive ultrasound and the cat is not a Persian or relted breed, we will test your cats on a research basis.  Please see Research and Join the Project!

Genetic Testing Information

Testing for Persian PKD can now be performed at an early age, with a small amount of DNA, and with nearly 100% accuracy. Buccal swabs can be used to collect DNA from the cat's mouth. Breeders can collect the samples in their own homes, no veterinary visits are required. The commercial DNA testing laboratories generally provide all the details for providing a sample and most supply testing "kits". Buccal swabs can be collected from the kittens at generally 8 - 10 weeks of age. The samples should not be taken directly after a kitten has eaten or nursed. The swabs are stable at room temperature, indefinitely, and can be shipped to any laboratory offering the test worldwide. Overnight courier services are not necessary, samples can be sent by regular mail.

A US patent has been filed for the feline PKD DNA test. Patents are likely to be filed in other countries also. The license for the test will be available to all interested laboratories provided they agree to the licensure terms.

The DNA testing laboratory at UC Davis, the Veterinary Genetics Laboratory, is working closely with the Lyons' laboratory to provide the PKD testing.

iHow to select a PKD testing laboratory

The following information reflects the opinion of Dr. Leslie Lyons and is not an endorsement for any laboratory and may or may not reflect the opinion of UC Davis. Dr. Lyons works closely with the UC Davis Veterinary Genetics Laboratory but also has many colleagues in animal testing laboratories throughout the world.

1) Get a DNA fingerprint with your PKD test

The results from the PKD test can be easily confused or purposely swapped between cats, thus breeders should strongly consider a PKD test that includes an identification panel of DNA markers, a.k.a. a DNA fingerprint. The DNA fingerprint is a unique identifier for the cat and can be confirmed at any time. By using the DNA fingerprint test in addition to the PKD test, parentage can be confirmed and the pedigrees validated. Horse registries have been using DNA identification for nearly 10 years to validate pedigrees. Dogs registries are also now performing DNA testing. Collection of the DNA samples can be performed by the breeders since a DNA fingerprint can always be challenged and proven. This eliminates any need for collection of samples by a third party, such as a veterinarian.

A standardized cat identification / parentage panel has been developed by the Lyons' laboratory and has been validated by a comparison test with over a dozen laboratories worldwide. Thus, a cat tested in the US should have the exact same results if re-tested in another laboratory in another part of the world. The cat DNA fingerprint test will help validate pedigrees and PKD results from any part of the world.

2) Confirm the reputation of the laboratory

The first laboratory to offer testing is not always the best! Well established DNA testing laboratories exist worldwide. These laboratories have had years of DNA-based testing in other species, such as horses and dogs. Breeders are encouraged to identify laboratories that have experience and/or can demonstrate proficiency with both PKD testing and DNA identification.  If you would like to have your service laboratory added to the list, please contact the laboratory at: felinegenome@ucdavis.edu

3) Pick a laboratory with good customer service, knowledge of cat and/or animal breeding, and are willing to counsel.

Cattery management and genetic counseling will be an important service once results are provided by the laboratory to the breeder. A service laboratory should be very willing to provide additional information, feedback and assistance with test interpretation and the implications for your breeding program.

4) Re-invest in cat research when possible

Some laboratories are not for profit, such as the UC Davis Veterinary Genetics Laboratory. All proceeds from animal DNA testing are used to improve research within the university and are not available to augment salaries of the VGL employees, Dr. Lyons, or the Lyons' Labortory employees. A majority of "profits" are reinvested in feline research to develop other genetic tests.

Test Costs

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Each testing laboratory can establish their own price for the cost of the PKD test. Since the DNA swabs are stable and can be shipped in the regular mail, breeders are advised to focus on reliability, reputation, customer service and investment in cat research for future genetic testing during the selection of their testing laboratory. Laboratories are generally willing to negotiate for lower testing costs if multiple tests are requested, such as coat color tests (agouti, brown, and color). Additionally, if groups or registeries can organized "bulk" shipments of samples and assist with data management, lower rates can be negotiated.

A portion of licensing revenues is returned to the University. Please see "University of California Patent Policy" for specific details.

Please contact the UC Davis Technology Transfer Center (530-757-3432) for further assistance and for information on the UC patent policy, procedures and licensure.

Cattery Management

Over 38% of Persian cats worldwide have PKD. Due to the high frequency of the disease, it is suggested that elimination of cats with PKD from breeding programs should be performed SLOWLY and CAREFULLY. Each cat with PKD has many good and important genes that should be maintained in the population, thus, mass neuter and spaying is NOT recommended. Most cats live long and healthy lives and do not suffer greatly from having the PKD mutation. Breeders should consider their entire breeding program as a whole and may consider to continue to breed cats with PKD. Breeding negative to positive cats would slowly eliminate the disease. Cats in subsequent generations that are PKD negative could be selected to replace inportant lines and particular cats. Ultrsound testing will determine what cats have mild and severe disease. Although the inheritance of severity is not understood, continued breeding of mildly affected cats is a conservation approach.

Continuing PKD Research

Several questions still remain for feline PKD. The identified mutation needs to be confirmed and VALIDATED in Persian cats worldwide and in other breeds. Our research laboratory will test any non-Persian breed on a research basis if ultrasound results and DNA from parents can be provided. Also, the test does not indicate severity of disease, thus, ultrasound clinics will continue, worldwide, in order to identify mild and severe cats that will help identify the modifying genes of this disease. Breeders are encouraged to participate in future ultrasound clinics.

Join the Project!

Breeders and cat owners cat assist the research for PKD in various ways. Some breeders have donated blood samples, PKD status and pedigree information for family studies. This information is still required for understanding disease severity. Others have donated blood samples from affected cats for mutation screening. Kidneys of deceased cats can be donated for analysis by researchers involved with human PKD studies. Collaborating owners can attend PKD clinics and have a majority of their cats screened for free or for a minimal cost. Some individuals choose to donate money to the Winn Foundation that is specifically marked for PKD research.

Contact the laboratory at UCDavis if you are interested in participating at: felinegenome@ucdavis.edu.

Information for sending samples can be found on this website at: DNA Sampling and Shipping Protocols

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PKD References

Other useful links:

Veterinary Genetics Laboratory (VGL)

Center for Companion Animal Health (CCAH)

California National Primate Research Center (CNPRC)

Center for Equine Health (CEH)

Department of Population Health & Reproduction (VM:PHR)

Last update: November 30, 2004 This site is under continual development. Please visit again soon! Many of the current pages are the place holders for future information. Please provide suggestions to the webmaster: felinegenome@ucdavis.edu