Test Allows Arabian Breeders to Scan for Inherited Neurologic Disorder

Equine cerebellar abiotrophy is a debilitating neurologic disorder that affects Arabian horses almost exclusively, and for which there is no treatment or cure. But, thanks to the work of veterinary researchers, breeders now have access to a new DNA test that could help them detect carriers of the condition so they do not propagate the problem in their herds.

The cerebellum is the part of the brain that plays an important role in the integration of sensory perception, coordination, and motor control. Equine cerebellar abiotrophy kills neurons in the cerebellum, causing head tremors and a lack of balance. Unfortunately, there is no treatment. Affected horses are routinely euthanized before adulthood because of the risk they pose to themselves and others.

Cecilia Penedo, PhD, a geneticist at the University of California, Davis, School of Veterinary Medicine's Veterinary Genetics Laboratory, said cerebellar abiotrophy is passed on 25% of the time when both parents are carriers of the gene.

"We really don't know what causes the variation, but it occurs," Penedo said.

Researchers at the Veterinary Genetics Laboratory have developed an indirect DNA test to help determine if a horse is a carrier. Penedo said the test, which is completed using a hair root sample and identifies markers associated with cerebellar abiotrophy, already has been used by a few breeders, and a few others have shown interest in the test.

While gene therapies to treat the disorder could become available in the future, Penedo said she doesn't expect to see them for years. Besides, the new test can front-load a solution to the issue.

"A cure is not needed if one doesn't produce affected foal," she said. "That is the goal, and that's the beauty of having a diagnostic test, because people can plan breedings. As long as they do not breed two carriers, they will not produce a cerebellar foal."

In August the Arabian Horse Foundation gave a $5,000 gift to the UC Davis Veterinary Genetics Laboratory for use on the cerebellar abiotrophy research project.

Learn more about cerebellar abiotrophy and the Veterinary Genetics Laboratory.  

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Robert S. Johnson

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