Many dog breeds have to deal with epilepsy, a disease which is genetically passed. In Finland, researchers have now found the genetc carrier for one of the many forms of epilepsy, and at the same time developed a test that can help breeders and veterinarians with the early detection of possible genetic abnormality.
In this case, it is a form of epilepsy that occurs mainly in the Rhodesian Ridgeback. Despite their powerful body, once intended to hunt lions, breed specific selection has also inserted the gene for epilepsy into the breed. Approximately 2 percent of Rhodesian Ridgebacks develop this form of epilepsy, called myklonisc epilepsy. A form that is already manifest at an early age, around six months. The attacks usually occur during rest on and may be triggered by light.
The first signs are usually involuntary muscle contractions in the rapidly growing pup. Of dogs who get the disease 2/3 is affected by the so-called Grand Mal's heavy attacks. Veterinary neurologist Professor Andrea Fischer (Small Animal Clinic, LMU Munich), molecular biologist Professor Hannes Lohi of the University of Helsinki and neurologist Professor Fiona James of the University of Guelph have sought to identify the responsible gene, and with success. It is a gene that plays a major role in a neurotransmitter controlling the operation of acetylcholine,a neurotransmittor is a substance that causes nerve impulses to transfer from one nerve to the other. The gene, DIRAS1, was until now, not associated with the occurrence of neurlogic disorders. But research in over 600 Ridgebacks and 1,000 other dogs did put this gene forward as a solidcandidate. In Ridgebacks approximately 15% of dogs indeed heve the DIRAS1 gene, and thus are carriers.
Most forms of canine epilepsy are multi genetic, and are transferred by a combination of genetic defects. With Ridgebacks it is but a single gene that is inherited recessive, i.e., two carriers can basically produce a sufferer, 1 in 4 pups would get statistically the disease when two carriers mate.
By selectively breeding within a limited population such genes thrive within a breed, and can keep such a derogation for a long time by breeding equally selective. The newly developed diagnostic test can prior to the mating prevent that two carriers possibly get sick puppies, simply by not breed with those two carriers. If puppies are to be examined afterwards, in fact 25% of them are carriers, but if those carriers will be excluded from breeding the disease may eventually be somewhat eliminated.
The study is also important,as the same form of epilepsy is common in humans. Further research must now determine whether also in humans this gene may play a role.