Retinal atrophy, Rod-cone dysplasia (RCD4)

 

Gene: C17H2orf71

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: Insertion, C17H2orf71 gene; c.3149 ins.C, p.(C1051V fs STOP 90nt)

Medical system: Ocular

Breeds: Australian Cattle Dog, English Setter, Gordon Setter, Irish Red and White Setter, Irish Setter, Japanese Spitz, Poodle - Miniature (Dwarf), Poodle - Moyen, Poodle - Standard, Poodle - Toy

Age of onset of symptoms: Around the age of 10 years

Progressive retinal atrophy refers to a family of genetic diseases that affect the retina, including degeneration of cone and rod receptor cells.  PRA-CRD-4 is a late onset disease in which clinical signs appear only around the age of 10, although changes in the retina can be seen on an ophthalmic examination after 3 years. The rods (weak light receptors) are the first cells to be affected so the animal will first begin to lose its night and peripheral vision.  The disease progresses gradually to affect the cones (color receptors) causing the animal to lose day vision and eventually become blind.

 

References:

OMIA link: [1575-9615]

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]

Karlskov-Mortensen P, Proschowsky HF, Gao F, Fredholm M. (2018) Identification of the mutation causing progressive retinal atrophy in Old Danish Pointing Dog. Anim Genet. 49(3):237-241. [pubmed/29624701]

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

Downs LM, Hitti R, Pregnolato S, Mellersh CS. (2014) Genetic screening for PRA-associated mutations in multiple dog breeds shows that PRA is heterogeneous within and between breeds.  Vet Ophthalmol. 17(2):126-30. [pubmed/29255994]

Downs LM, Bell JS, Freeman J, Hartley C, Hayward LJ, Mellersh CS. (2013) Late-onset progressive retinal atrophy in the Gordon and Irish Setter breeds is associated with a frameshift mutation in C2orf71. Animal Genetics 44(2):169-177. [pubmed/22686255]