Progressive Retinal Atrophy (Giant Schnauzer Type)
Affected Genes: NECAP1
Inheritance: Autosomal Recessive
Variant(canFam6):
chr27:9147344: C>T
Breed: Dachshund
German Spitz
German Spitz Klein
Giant Schnauzer
Keeshond
Miniature Longhaired Dachshund
Miniature Smooth Dachshund
Pomeranian
Pomsky
General Information: Progressive Retinal Atrophy (PRA) in Giant Schnauzers involves the gradual deterioration of rod and cone photoreceptor cells within the retina, crucial for low-light and color vision, respectively. Initial symptoms typically appear around the age of 4, starting with subtle changes in night vision and progressing to noticeable difficulties in brighter conditions. Over time, affected dogs may experience a noticeable change in the reflectivity and appearance of the tapetum—a reflective layer behind the retina—along with thinning of the retinal blood vessels, detectable during veterinary eye examinations. This condition invariably progresses to complete blindness, with the rate of progression varying among individual dogs.
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 Progressive Retinal Atrophy (PRA) in Giant Schnauzers targets mutations in the NECAP1 gene to identify carriers who may pass on the disorder to their offspring. This disease is transmitted as an autosomal recessive trait, meaning a dog must inherit two copies of the faulty gene—one from each parent—to exhibit symptoms. Carriers, possessing only one copy, typically do not show any signs of the disease but have a 50% chance of passing the mutation to their offspring. When two carriers are bred, each puppy has a 25% chance of being affected by PRA and a 50% chance of being a carrier. Early genetic screening is vital to guide breeding decisions and prevent the birth of affected pups. By avoiding the mating of carriers, breeders can help reduce the prevalence of PRA within the breed, ensuring healthier future generations. As with all genetic testing, it's important to consider that a clear test result for NECAP1 mutations does not rule out other forms of PRA or similar conditions, underscoring the need for comprehensive health strategies in breeding practices.
References:
Hitti RJ, Oliver JAC, Schofield EC, Bauer A, Kaukonen M, Forman OP, Leeb T, Lohi H, Burmeister LM, Sargan D, Melleresh CS. Whole Genome Sequencing of Giant Schnauzer Dogs with Progressive Retinal Atrophy Establishes NECAP1 as a Novel Candidate Gene for Retinal Degeneration. Genes (Basel) 2019 10(5):385.