Progressive Retinal Atrophy, Cone-Rod Dystrophy (Dachshund Type)
Affected Genes: NPHP4
Inheritance: Autosomal Recessive
Variant(canFam6):
chr5:59924215-59924392: 180 bp deletion
Breed: Dachshund
Miniature Longhaired Dachshund
Miniature Smooth Dachshund
Miniature Wirehaired Dachshund
Standard Longhaired Dachshund
Standard Smooth Dachshund
Standard Wirehaired Dachshund
General Information: Progressive Retinal Atrophy, Cone-Rod Dystrophy 4 (PRA-crd4) in Dachshunds involves the gradual deterioration of both rod and cone photoreceptor cells in the retina, crucial for night and daylight vision, respectively. Detectable through an electroretinogram as early as 5 weeks of age, this condition usually remains clinically unnoticeable until significant symptoms appear between 10 months and 3 years. Initially, affected dogs suffer from day blindness due to the degeneration of cone cells, followed by night blindness as the rod cells also deteriorate. Most dogs with this condition experience total retinal atrophy and complete blindness by around 6 years of age, although the progression can vary between individuals.
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 NPHP4 gene mutation helps identify carriers of Progressive Retinal Atrophy, Cone-Rod Dystrophy 4 (PRA-crd4), which is crucial for informed breeding decisions. This disorder is autosomal recessive, requiring a dog to inherit two copies of the defective gene—one from each parent—to manifest the disease. Carriers, possessing only one copy, do not show symptoms but may pass the mutation to offspring. Breeding two carriers yields a 25% chance each puppy will inherit the disease and a 50% chance it will be a carrier. Responsible breeding practices are vital, including avoiding mating between known carriers, to prevent the transmission of this mutation and reduce the incidence of affected dogs. Genetic testing before breeding is recommended to ensure that dogs not carrying the mutation are bred, maintaining the health of future generations and minimizing the disease's prevalence.
References:
Palanova A, Schroffelova D, Pribanova M, Dvorakova V, Stratil A. Analysis of a deletion of the nephronophthisis 4 gene in different dog breeds. Vet Ophthalmol. 2013 17(1):76-78.
Ropstad EO, Bjerkas E, Narfstrom K. Clinical findings in early onset cone-rod dystrophy in the standard wire-haired dachshund. Vet Ophthalmol. 2007 10(2):69-75.
Wiik AC, Thoresen SI, Wade C, Lindblad-Toh K, Lingaas F. A population study of a mutation allele associated with cone-rod dystrophy in the standard wire-haired dachshund. Anim Genet. 2009 40(4):572-574.
Wiik AC, Wade C, Biagi T, Ropstad EO, Bjerkås E, Lindblad-Toh K, Lingaas F. A deletion in nephronophthisis 4 (NPHP4) is associated with recessive cone-rod dystrophy in standard wire-haired dachshund. Genome Res. 2008 18(9):1415-1421.