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Dominant PRA (PRA-D)

Dominant Pra (PRA-D)

Progressive Retinal Atrophy (Bullmastiff/Mastiff Type)

Dominant PRA (PRA-D) is an eye disorder that affects English Mastiffs and Bull Mastiffs. It is a form of Progressive Retinal Atrophy (PRA) that causes cells of the eye to deteriorate over time eventually leading to complete blindness. Typically, affected dogs show symptoms of the disease starting at approximately 2-3 years of age. However, symptoms including night blindness have been observed in puppies as young as 6 weeks. Progression of the disease is fairly quick with most affected dogs suffering complete blindness within 1-2 years from the onset of symptoms. This particular type of PRA seen in the Mastiff breeds is a dominant condition which means a dog only needs to inherit one copy of the mutation to be affected by the disease.

Reading Your Results


These dogs have two copies of the normal gene and will neither develop Dominant PRA nor pass this mutation to their offspring.


These dogs have one copy of the normal gene and one copy of the mutation associated with this disease. They will develop Dominant PRA and will, if bred, pass the mutation to 50% of its offspring, on average.


These dogs have two copies of the mutation associated with Dominant PRA which results in visual deterioration and eventual blindness.

Additional Details


Autosomal Dominant

Affected gene



Ch. 20


Chr20:5637394 (CanFam3): C>G


Kijas JW, Cideciyan AV, Aleman TS, Pianta MJ, Pearce-Kelling SE, Miller BJ, Jacobson SG, Aguirre GD, Acland GM. Naturally occurring rhodopsin mutation in the dog causes retinal dysfunction and degeneration mimicking human dominant retinitis pigmentosa. Proc Natl Acad Sci U S A. 2002 Apr 30; 99(9):6328-33. [PubMed: 11972042]