Progressive Retinal Atrophy – PRA is inherited and causes progressive blindness in the affected dogs. Many pure breeds have one or another form of PRA, with a few forms now detectable by DNA-based genetic tests.
Cases of PRA in Sloughis have been documented repeatedly. The Sloughi PRA disease has late onset with first noticeable signs of vision loss usually evident at 2 to 3 years of age. The inheritance pattern of this disease is autosomal recessive, meaning a dog is affected when it inherits one disease gene from each parent, where each parent is either a carrier or affected with PRA.
Although PRA can't be treated, it can be prevented. The DNA-based test provides a method to eliminate Progressive Retinal Atrophy from the Sloughi. This test is done on a small sample of blood and detects the genetic defect responsible for the disease. The genetic defect is in the PDE6B gene, also referred to as rcd1a, the same gene that harbors another defect causing PRA in Irish Setters.
The key to preventing autosomal recessive diseases lies in identifying dogs that do not carry the defective genes. This test unequivocally and reliably identifies normal dogs. Called "genetically clear," "noncarriers" or, more formally, "homozygous normals," such dogs can pass only the normal gene on to all their pups. This means that none of their pups can ever be affected with PRA. These clear dogs can be bred to any mate, even to PRA-affected dogs that may be desirable breeding prospects for other reasons.
As a mutation-based test, this procedure also identifies carriers and affecteds with 100% accuracy. But while a clear dog may be bred to any other dog, carriers and affecteds must be bred only to clear dogs. Desirable breedings include at least one parent proven "normal" by the DNA-based PRA test, as shown in the shaded areas of the following table. Breeding untested dogs or breeding two carrier dogs puts you at risk of producing PRA-affected pups.
Pups can be tested to distinguish normals, carriers, and affecteds as soon as they are old enough to have a small amount of blood collected for testing.
OptiGen offers the Sloughi PRA test through cooperation with Dr. Epplen and the scientific team who discovered this genetic defect in Sloughis at the Department of Molecular Human Genetics, Ruhr University, Bochum, Germany.
PCR technology is performed under a license agreement with Roche Molecular Systems, Inc.
Learn more about this disease at: http://sloughi.tripod.com/sloughisonline/PRA.html.
Page last updated February 07, 2006
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