Breakthrough discovery leads to powerful genetic test

From a cross-posted email sent to the Can-Gen-Ec list:

The challenge was posed nearly forty years ago; the trail has been hot for the last two. Long-standing partnerships have resulted in advances in diagnosing and understanding hip dysplasia in dogs, a disease that occurs when a specific combination of genes exists and results in hip osteoarthritis and disability.

Research indicates that, in addition to Labrador Retrievers, discoveries in the diagnosis and treatment of hip dysplasia will assist other breeds including Border Collies, Golden Retrievers, Great Danes, Rottweilers, German Shepherds and Newfoundland dogs, and has the potential to offer insights into similar diseases in other mammals.

In 2007, with grant support from the Morris Animal Foundation and Pfizer Incorporated, Dr. George Lust and colleagues Dr. Rory Todhunter, Steven Friedenberg and Dr. Zhiwu Zhang discovered the first panel of genetic markers that could lead to genetic testing for the diagnosis of canine hip dysplasia. With a new sample of dogs, they plan to verify the accuracy of this panel of genetic markers for hip conformation that can predict the breeding value of the dog.

A breakthrough in diagnosis, these genetic tests are expected to be more accurate than current procedures, less expensive to perform, and enable earlier identification of both normal dogs and those at risk for hip dysplasia. Genetic tests may also reduce the need for progeny testing.

"This has been a long-sought goal," says Dr. Lust. "Now, with one DNA sample we are on the road to telling if a young dog will develop normally. We will not need to wait until the dog is old enough to undergo the current radiographic screening." The research team also identified a mutation in the gene for fibrillin 2 that segregates in a sample of dysplastic dogs and nondysplastic dogs. Fibrillin 2 is a gene expressed in the tissue o f hip joints. This is the first gene reported to be associated with canine hip dysplasia. The discovery opens opportunities for defining the biochemical basis of the disease.

In other related research, Dr. Lust partnered with Dr. Bernard G. Steinetz at the New York University Medical Center to study the relationship of two milk-borne hormones--- relaxin and estrogen---to the onset of hip dysplasia. In a controlled study, the investigators concluded that early anti-hormone treatments may be able to negate the effects of the milk-borne hormones as they relate to induction of canine hip dysplasia.

Exerpted from: The Baker Institute Annual Report 2008

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