Test Detail
Dominant PRA (Bullmastiff and English Mastiff)
Ocular · Dog
Molecular test for autosomal dominant progressive retinal atrophy described in the English Mastiff due to the T4R variant of the RHO gene and also reported in the Bullmastiff, although in the latter breed the association with T4R is not confirmed. Retinal degeneration leads to progressive blindness. The test reports clear/carrier/affected status for the RHO T4R variant.
Incidence
Main breed: English Mastiff, where the T4R variant is confirmed. In the Bullmastiff the finding is heterogeneous and does not allow T4R to be confirmed as the cause; carrier frequencies are not published systematically (limited data).
Breeder management
- Genotype breeding animals before mating\n- Because of dominant inheritance: an animal with the variant (heterozygote or homozygote) can transmit it to the offspring; mating two animals with the variant is inadvisable\n- An affected animal must not be bred; a carrier of the variant should be mated to a clear animal\n- After a confirmed clinical case, do not repeat the parental mating and communicate the status to the buyer
Specialist notes
Complementary annual ocular examination (ECVO) to confirm the disease and follow its progression. Differentiate RHO dominant PRA from other recessive PRAs of the Bullmastiff/Mastiff (if any) by age of onset and fundus pattern. Dominant inheritance requires follow-up with periodic ocular examination in any animal with the variant. Rule out other causes of progressive blindness (uveitis, glaucoma, retinal detachment) before attributing the picture to dominant PRA.
References
1. Kijas JW et al. 2002. Naturally occurring rhodopsin mutation in the dog causes retinal dysfunction and degeneration mimicking human dominant retinitis pigmentosa. Proc Natl Acad Sci U S A 99:6328-6333. PMID: 11972042
2. Kijas JW et al. 2003. Canine models of ocular disease: outcross breedings define a dominant disorder present in the English mastiff and bull mastiff dog breeds. J Hered 94:27-30. PMID: 12692159
3. OMIA:001346-9615 - Retinal atrophy, progressive, autosomal dominant, RHO-related. https://omia.org/OMIA001346/9615/
2. Kijas JW et al. 2003. Canine models of ocular disease: outcross breedings define a dominant disorder present in the English mastiff and bull mastiff dog breeds. J Hered 94:27-30. PMID: 12692159
3. OMIA:001346-9615 - Retinal atrophy, progressive, autosomal dominant, RHO-related. https://omia.org/OMIA001346/9615/