Polycystic kidney disease QPCR
The Molecular Diagnostic Unit has been offering a genetic test to diagnose autosomal dominant polycystic kidney disease (AD-PKD) in cats since April 2005. This genetic test is a QPCR and evaluations of the test have shown excellent agreement with the results of ultrasound screening. This test will revolutionise testing for AD-PKD.
AD-PKD is a very common problem in Persian cats and related breeds, especially Chinchillas and Exotic Shorthairs. The Feline Advisory Bureau (FAB) has established a UK PKD screening scheme to assist cat breeders in identifying affected cats before they are used for breeding. Until recently specialist ultrasound scanning has been required for this, but the identification of a specific genetic mutation associated with feline AD-PKD means that PCR can now be used to identify affected cats. Cats screened for AD-PKD using the Langford Veterinary Services QPCR can now be included in the FAB Scheme, and cats found to be negative for the disease can be listed on the FAB PKD negative register. Confirmation of the cat’s identity is an essential part of the screening scheme, so veterinary surgeons must ensure that all cats that are to be included in the FAB scheme are microchipped, and that their chip number is recorded by the veterinary surgeon at the time the cat is sampled. For more information about AD-PKD and the FAB UK PKD Screening Scheme visit the FAB web-site or contact the FAB office (01747 871872).
Please note: For Inclusion on the FAB PKD Negative Register, the sample submitted for PKD testing MUST be taken by a veterinary surgeon and labelled with the cat's microchip number.
The assay requires either 0.5ml of EDTA anticoagulated blood or a buccal swab sample.
Update: In late 2008, due to ongoing research and development work within the Molecular Diagnostic Unit, we discovered that a very small percentage of cats (3 out of 1500; 0.2%) had extra genetic mutations that may have interfered with the AD-PKD diagnostic assay. As such, since November 2008 ALL samples submitted for AD-PKD testing have been run with two QPCR assays, both targetting the known mutation but using different PCR primer sets. This significantly reduces the risk of an incorrect result being caused by one of a pair of PCR primers not binding to either the normal or mutant gene sequence due to these extra genetic mutations (a phenomenon known as allele drop out).
The following graph shows the number of samples submitted to the Molecular Diagnostic Unit for PKD genetic testing in the years 2005 to 2009, and the percentage of affected cats. This clearly shows a decline in the percentage of cats testing positive for the AD-PKD genetic mutation, which is likely due to selective breeding and AD-PKD screening by breeders.
Further information
- Taking a buccal mucosal DNA sample
- Feline polycystic kidney disease: from ultrasound to genetic testing
- More information about polycystic kidney disease can be found on the Feline Advisory Bureau website.
- For more information about this assay please see our publications