Retinal atrophy, progressive (CNGA1 related)

 

Gene: CNGA1

Transmission: Autosomal recessive

For an autosomal recessive genetic disease an animal must have two copies of the mutation in question to be at risk of developing the disease.  Both parents of an affected animal must be carriers of at least one copy of the mutation.  Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

Mutation: Deletion, CNGA1 gene; c. 1752_1755 del.4bp, p.(T585S fs STOP 7 nt), exon9

Medical system: Oculaire

Breeds: American Staffordshire Terrier/Amstaff, English Bulldog, Labrador Retriever, Schnauzer - Miniature, Shetland Sheepdog

Age of onset of symptoms: variable in onset, on average around 5 years of age

Progressive retinal atrophy in Shetland Sheepdog (PRA) is a degenerative disease that affects photoreceptor cells in the retina. Symptoms include various bilateral and symmetrical changes in the retina, such as increased reflectivity of tapetum lucidum, vascular attenuation, pigmentation change, and even atrophy of the optic nerve. This disease eventually leads to blindness. It should be noted that the mutation in the CNGA1 gene is one cause of PRA in Shetland Sheepdog, but that the genetics of the disease is complex and it is suspected that there are other genetic components that remain to be identified.

 

References:

OMIA link: [1977-9615]

Donner J, Freyer J, Davison S, et al. (2023) Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs.  PLoS Genet. 19(2):e1010651. [pubmed/36848397]

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]

Bunel M, Chaudieu G, Hamel C, Lagoutte L, et al. (2019) Natural Models for Retinitis Pigmentosa: Progressive Retinal Atrophy in Dog Breeds.  Hum Genet. 138(5):441-453. [pubmed/30904946]

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

Wiik AC, Ropstad EO, Ekesten B, et al. (2015) Progressive retinal atrophy in Shetland sheepdog is associated with a mutation in the CNGA1 gene. Animal Genetics. [pubmed/26202106]