Einstein Science Reporting for Kids
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7-Jan-2005

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Dog epilepsy gene



A miniature wirehaired dachsund with a form of epilepsy known as Lafora disease in humans. More than 5 percent of dogs in this breed have the disease, due to recurring Epm2b mutations and inbreeding. Image courtesy of Drs. Clare Rusbridge and Berge Minassian.
Click here for a high resolution photograph.

Epilepsy, a condition that affects the nervous system, is more common in dogs than it is in humans. Both dogs and humans with the disease can lead healthy, normal lives, but it causes seizures that can sometimes be dangerous.

Scientists have now identified a genetic mutation responsible for epilepsy in dogs. With this information, they have also developed a test that can determine whether a dog has the mutation. Dog owners might someday use this test to help make sure they are breeding healthy dogs.

The study appears in the 07 January 2005 issue of the journal Science.

The research also shows that studying dog genes can be useful for understanding human diseases. Because of the way that dogs are bred, some dog versions of diseases can be more common in certain breeds and easier to study than they are in humans.

For example, more than 5 percent of the purebred Miniature Wirehaired Dachshunds in the United Kingdom have a certain type of epilepsy. The dogs have small seizures that make their teeth chatter and their eyes blink rapidly, and sometimes they have more severe seizures that make them unconscious for short periods of time. Hannes Lohi of the Hospital for Sick Children in Toronto, Canada and his colleagues figured out that the Dachshunds had a form of epilepsy that's called "Lafora disease" in humans.



A miniature wirehaired dachshund wears sunglasses to minimize light induced seizures. Image courtesy of Drs. Clare Rusbridge and Berge Minassian
Click here for a high resolution photograph.

Lafora disease is extremely rare in people, but it occurs more frequently in Basset Hounds, Poodles, Pointers, Dachshunds and other purebred dogs. It's a very serious disease in humans but it's a lot milder in dogs.

The mutation that Lohi and his colleagues identified occurred in the Miniature Wirehaired Dachshunds and other dogs with the disease, and it can also occur in other closely related species like wolves and coyotes. Each animal needs to inherit a mutated copy of the gene from both its mother and father in order for the gene to cause epilepsy.

This means that the disease is more likely to occur in small populations like purebred dogs. One of the Science authors, Berge Minassian of the Hospital for Sick Children, noted that the mutation could also cause problems in the wild.

"If a species is endangered and has only few members, if the mutation occurs, say in an endangered wolf, it could cause trouble for the species," he said.

Further research on dogs with this mutation might help researchers better understand how to treat or prevent seizures in humans with Lafora disease, according to the authors.

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