Progressive Retinal Atrophy (Irish Setter Type)
Affected Genes: PDE6B
Inheritance: Autosomal Recessive
Variant(canFam6):
chr3:94213218: C>T
Breed: Irish Red and White Setter
Irish Setter
Irishdoodle
General Information: Progressive Retinal Atrophy, Rod-Cone Dystrophy 1 (PRA-rcd1) specifically affects Irish Setters, beginning as early as one month of age with noticeable symptoms. Initially, affected puppies exhibit signs of night blindness and a loss of peripheral vision due to the degeneration of rod cells, which are crucial for low-light vision. The condition quickly escalates, leading to complete blindness under all light conditions by approximately one year of age. This rapid progression includes a visible change in the tapetum—a reflective layer behind the retina—observable during veterinary eye examinations, indicating advanced retinal damage.
How to Read Your Dog's Test Results for this Genetic Variant:
Two Variants Detected: Dog Likely Affected
One Variant Detected: Dog Unlikely Affected
No Variants Detected: No Effect
Gene / Testing Information: Genetic testing for the PDE6B gene in Irish Setters identifies carriers of Progressive Retinal Atrophy, Rod-Cone Dystrophy 1 (PRA-rcd1), providing crucial information for breeders. This form of progressive retinal atrophy follows an autosomal recessive inheritance pattern, requiring two copies of the mutated gene for the disease to manifest. Dogs carrying only one copy of the mutated gene do not show symptoms but can pass the mutation onto their offspring. Breeding two carriers results in a 25% chance of producing affected offspring and a 50% chance that each puppy will be a carrier. To prevent the propagation of this debilitating condition, it is recommended to avoid breeding carriers together. Screening through genetic tests before breeding can help eradicate this mutation from the gene pool and prevent the birth of affected puppies. While dogs clear of this mutation pose no increased genetic risk for PRA-rcd1, a normal result does not rule out other forms of PRA due to different mutations, nor does it exclude other potential genetic diseases.
References:
Aguirre GD, Baldwin V, Weeks KM, Acland GM, Ray K. Frequency of the codon 807 Mutation in the cGMP phosphodiesterase beta-subunit gene in Irish Setters and other dog breeds with hereditary retinal degeneration. J Hered. 1999 90(1):143-7.
Maroudas P, Jobling AI, Augusteyn RC. Genetic screening for progressive retinal atrophy in the Australin population of Irish Setters. Aust Vet J. 2000 78(11):773-774.
Petersen-Jones SM, Clements PJM, Barnett KC, Sargan DR. Incidence of the gene mutation causal for rod-cone dysplasia type 1 in Irish setters in the UK. J Small Anim Pract. 1995 36(7):310-314.
Suber ML, Pittler SJ, Qin N, Wright GC, Holcombe V, Lee RH, Craft CM, Lolley RN, Baehr W, Hurwitz RL. Irish setter dogs affected with rod/cone dysplasia contain a nonsense mutation in the rod cGMP phosphodiesterase beta-subunit gene. Proc Natl Acad Sci USA. 1993 90(9):3968-3972.