A RARE neurological condition has been identified in a small number of Hungarian Vizslas.
Cerebellar ataxia is an aggressive and progressive condition which affects gait and co-ordination from about two to three months of age and for which there is no treatment.
Dogs affected have to be put to sleep on welfare grounds when the disease reaches advanced stages.
At present, the carrier rate is estimated to be about one in every 100 Vizslas. The Wirehaired variety is thought not to be affected.
The genetic mutation responsible has been discovered by researchers at the Kennel Club Genetic Centre at the Animal Health Trust (AHT) in association with the neurology team at the Royal Veterinary College. A DNA test for it, at £48, is available from the Animal Health Trust DNA testing service at www.ahtdnatesting.co.uk.
In order to find the mutation responsible the AHT used whole genome sequencing technology to study all 2.4 billion letters of DNA from just one affected Vizsla. Traditionally, a genetic investigation into a disease of this nature would require DNA samples from at least 12 affected dogs and the same number of healthy control dogs from the same breed. But advanced genome sequencing technology and the use of state-of-the-art computer analysis allows every letter of DNA from a single affected dog to be ‘interrogated’ and compared to a bank of genome sequences of healthy dogs from different breeds, in order to find the change in DNA responsible for a specific inherited disease.
This approach allowed the genetics of cerebellar ataxia in the Vizsla to be investigated straight away without collecting additional DNA samples.
The causal mutation was identified quickly as a single letter change in the DNA code. Once it had been pinpointed it was confirmed by screening healthy Vizsla DNA samples. Only the Vizslas with cerebellar ataxia had two copies of the genetic mutation needed to cause the disease.
Genetics Centre head Dr Cathryn Mellersh said: “Normally in our genetic investigations it can be really challenging to look for a genetic mutation when we only have DNA from one or two affected dogs. However, that’s no longer the case. By using whole genome sequencing technology, the same technology which is at the heart of our Give a Dog a Genome research project to create the UK’s largest canine genome bank, it is much, much easier to look closely at all of the DNA in a dog’s genome and it’s possible to find a rare genetic mutation relatively quickly by comparing that genome with the genomes of healthy dogs from different breeds.
“The identification of this mutation and the development of a DNA test demonstrate the huge potential of the Give a Dog a Genome project and prove how gaining a wealth of new information about the canine genome from a vast number of breeds will enable us to find genetic mutations much more effectively in the future.”
At present the condition is ‘quite rare’ in the breed, Dr Mellersh said.
“So we’re not expecting to find several affected dogs through DNA testing, but it’s crucial to identify any possible carriers in order to prevent any more puppies being born with this horrible disease and to stop it becoming a bigger problem in future lines.
“We’ve had a good level of interest in this research so far from breeders and we’re confident that the Vizsla-breeding community is keen to get this mutation under control, and in time, eradicate it safely from their breed altogether.”
For more information about the Give a Dog a Genome project, visit www.aht.org.uk/gdg.