The Animal Health Trust (AHT) has launched a new test after identifying a rare neurological condition in a small number of smooth-haired Hungarian vizslas.
Cerebellar ataxia is an aggressive and progressive condition affecting gait and coordination in the breed from around two to three months of age, which has no treatment. Affected dogs are euthanased on welfare grounds at the advanced stages of the disease.
The genetic mutation responsible has been discovered by researchers at the Kennel Club Genetics Centre at the AHT, in association with the neurology team at the RVC.
In order to find the mutation, the AHT used whole genome sequencing technology to study all 2.4 billion letters of DNA from one affected vizsla.
Traditionally, a genetic investigation into a disease of this nature requires samples from at least 12 affected dogs and the same number of healthy control dogs from the same breed. Now, advanced genome sequencing technology and state-of-the-art computer analysis allows every letter of DNA from an affected dog to be interrogated and compared to a bank of genome sequences of healthy dogs in order to find the change in DNA responsible for a specific inherited disease.
This approach allowed the genetics of cerebellar ataxia in the Hungarian vizsla to be investigated straight away, without collecting additional DNA samples.
The causal mutation was identified as a single letter change in the DNA code. Once this mutation had been pinpointed, it was confirmed by screening healthy Hungarian vizsla DNA samples. Only the Hungarian vizslas with cerebellar ataxia had two copies of the genetic mutation needed to cause the disease.
Cathryn Mellersh, head of the Kennel Club Genetics Centre at the AHT, 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 at the heart of our Give a Dog a Genome research project to create the UK’s largest canine genome bank, it is 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.”
She added: “As this condition in the Hungarian vizsla is quite rare, we’re not expecting to find several affected dogs through DNA testing, but it is crucial to identify any possible carriers in order to prevent any more puppies being born with this horrible neurological disease, and to stop it becoming a bigger problem in future lines.
“The carrier rate for this condition is estimated at approximately one in every 100 smooth-haired Hungarian vizsla. We’ve had a good level of interest in this research so far from vizsla breeders and we’re confident 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