Progressive Retinal Atrophy, Cone-Rod Dystrophy 4, Progressive Retinal Atrophy-cord1, Progressive Retinal Atrophy-crd4, Progressive retinal atrophy-crd4/cord1, PRA-cord1, PRA-crd4, PRA-crd4/cord1
Progressive Retinal Atrophy (PRA) is a category of different progressive conditions leading to retinal atrophy and potential blindness. Cone-Rod dystrophy 4 (PRA-CORD1-CRD4) is an inherited eye disease affecting Dachshunds and English Springer Spaniels that leads to degeneration of both retinal rod and cone cells affecting vision in both low and bright light. Onset of symptoms can be seen starting at less than a year old until about 5 years of age with the average being around 3 years of age. However, the onset can vary significantly with dogs as old as 15 years being diagnosed. This mutation shows what is known as incomplete penetrance which means dogs that carry two copies of the mutation may not develop symptoms of the disease which would suggest other factors either genetic or environmental may play a role in disease progression. Following diagnosis, the disease can progress slowly but typically leads to complete blindness.
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These dogs have two copies of the normal gene and will neither develop PRA-CORD1-CRD4 progressive retinal atrophy nor pass this mutation to their offspring.
B. (CARRIER/NOT AFFECTED):
These dogs have one copy of the normal gene and one copy of the mutation associated with this disease. They will not develop PRA-CORD1-CRD4 progressive retinal atrophy but will, if bred, pass the mutation to 50% of its offspring, on average.
C. (AT RISK/AFFECTED):
These dogs have two copies of the mutation associated with PRA-CORD1-CRD4 progressive retinal atrophy and are susceptible to degeneration of both retinal rod and cone cells affecting vision.
Autosomal Recessive With Incomplete Penetrance
Chr15:18332036-18332037 (CanFam3): 44 Bp Insertion (Ins(A)29GGAAGCAACAGGATG) Or 59 Bp Insertion (Ins (A)44GGAAGCAACAGGATG)
Mellersh CS, Boursnell ME, Pettitt L, Ryder EJ, Holmes NG, Grafham D, Forman OP, Sampson J, Barnett KC, Blanton S, Binns MM, Vaudin M. Canine RPGRIP1 mutation establishes cone-rod dystrophy in miniature longhaired dachshunds as a homologue of human Leber congenital amaurosis. Genomics. 2006 Sep; 88(3):293-301. [PubMed: 16806805]