Dominant (PRA)



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Dominant PRA


Dominant PRA is an autosomal dominant trait and a form of Progressive Retinal Atrophy that affects English Mastiffs and Bullmastiffs. PRA is an eye disorder that causes the rod and cone cells to deteriorate over time, eventually leading to complete blindness. Dogs that are affected by this disorder often appear to have clinically normal eyes until around age 2-3 years old when the cells begin to die and vision loss increases. Some pups show signs of night-blindness by 6 weeks of age. By the age of 3-4 years most affected dogs are completely blind.

As the name suggests, PRA in the Mastiff breeds is a dominant condition. This means that a dog only needs to inherit one copy of the defective gene to be affected by the disease. A dog that is homozygous affected (meaning he has two copies of the mutation) will always produce affected offspring. A dog that is heterozygous affected (meaning that he only has one copy of the mutation) could pass on either allele to his offspring. This makes DNA testing an important tool, as the disease is often not detected until a dog has already been bred.

Sample Type:

Animal Genetics accepts buccal swab, blood, and dewclaw samples for testing. Sample collection kits are available and can be ordered at test now.

Test Is Relevant To the Following Breeds:

English Mastiff, Bullmastiff


Animal Genetics offers DNA testing for Dominant PRA. The genetic test verifies the presence of the Dominant PRA Gene and presents results as one of the following:

PRA/PRA Affected The dog carries two copies of the mutant gene and is homozygous for Dominant PRA. This dog will be affected and will always pass on the defective gene, producing all affected puppies.
PRA/n Affected Both the normal and mutant copies of the gene detected. The dog is affected by PRA and could pass on either the normal or mutant allele to any offspring.
n/n Clear Dog tested negative for the Dominant PRA mutation and will not pass on the defective gene to its offspring.