Retinal atrophy, progressive, autosomal dominant

Gene: RHO

Transmission: Autosomal dominant

For an autosomal dominant genetic disease, an animal must have at least one copy of the mutation in question to be at risk of developing the disease.  Animals with two copies of the mutation generally have more severe symptoms and an earlier onset of the disease than animals with just one copy of the mutation.  One or both of the parents of an animal with the mutation has one or two copies of the mutation.  Animals that have one or two copies of the mutation can pass the mutation on to future generations.

Mutation: Substitution, RHO gene ; c.11 C>G, p.(T4R), exon1

Medical system: Ocular

Breeds: Bullmastiff, Mastiff (Old English)

Age at onset of clinical signs: Around 18 months of age

PRA-Dominant, or progressive retinal atrophy, is a genetic disorder involving degeneration of the rods in the retina. Rods are the photoreceptors in the retina that enable vision in twilight and also peripheral vision. The first signs observed by a veterinary ophthomologist involve a change in the appearance of the structure behind the retina, the tapetum lucidum.  Clinically, affected animals begin to show a loss of night and peripheral vision. The disease is progressive, leading eventually to complete blindness sometimes after several years of life. Dogs with both mutated copies of the gene will progress more rapidly than those with a single mutation.

OMIA link: [1346-9615]

Genetics Committee of the American College of Veterinary Ophthalmologists. (2021) The Blue Book: Ocular disorders presumed to be inherited in purebred dogs. 13th Edition.  [https://ofa.org/wp-content/uploads/2022/10/ACVO-Blue-Book-2021.pdf]

Sudharsan R, Simone KM, Anderson NP, et al. (2017) Acute and Protracted Cell Death in Light-Induced Retinal Degeneration in the Canine Model of Rhodopsin Autosomal Dominant Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 58(1):270-281. [pubmed/28114588]

Palanova A. (2016) The genetics of inherited retinal disorders in dogs: implications for diagnosis and management.  Vet Med (Auckl). 7:41-51. [pubmed/30050836]

Kijas JW, Miller BJ, Pearce-Kelling SE, Aguirre GD, Acland GM. (2003) Canine models of ocular disease: outcross breedings define a dominant disorder present in the English mastiff and bull mastiff dog breeds. J Hered. 94(1):27-30. [pubmed/12692159]

Kijas JW, Cideciyan AV, Aleman TS, et al. (2002) Naturally occurring rhodopsin mutation in the dog causes retinal dysfunction and degeneration mimicking human dominant retinitis pigmentosa. Proc Natl Acad Sci USA 99(9):6328-33. [pubmed/11972042]