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PRA-RCD1 Irish Setter Type (Progressive Retinal Atrophy)
| Acronym: | PRA-RCD1 |
| Gene: | PDE6B |
| Mutation: | c.2421G>A |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
PRA-RCD1 Irish Setter type is a genetic disorder that belongs to a group of disorders known as progressive retinal atrophy. Progressive retinal atrophy (PRA) comprises autosomal recessively inherited diseases that lead to degeneration of retinal photoreceptor cells in dogs and other pets. In general, these diseases are characterized by disturbance of vision in the dark, visual field defects, and abnormalities in the electroretinogram, which can progress to blindness. The age of onset and rate of retinal degeneration varies between the different forms of the conditions. Some forms of PRA are common to multiple dog breeds, while others are recognized in just a single breed. Rod-cone dysplasias are a group of recessively inherited diseases with early onset where photoreceptors are disturbed in their normal development and never manage to develop properly. The progression of rod-cone dystrophy is caused by sequential degeneration of rod and cone photoreceptors.
In PRA-RCD1 affected Irish setters retina and photoreceptor development appears normal until 13 days of age, but subsequent development of rod photoreceptor cells is arrested. Rod photoreceptor degeneration is evident by 1 month of age, nearly all of the rod photoreceptors have degenerated by 5 months, and cone photoreceptor degeneration is completed by about 1 year. PRA-RCD1 cannot be treated, but it can be prevented with genetic testing prior to breeding. Breedings of untested dogs or dogs tested as carriers are at risk of producing PRA-RCD1 affected pups.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Dekomien, G., Runte, M., Gödde, R., and Epplen, J.T. (2000). Generalized progressive retinal atrophy of Sloughi dogs is due to an 8-bp insertion in exon 21 of the PDE6B gene. Cytogenet. Cell Genet. 90, 261–267.
Kukekova, A.V., Goldstein, O., Johnson, J.L., Richardson, M.A., Pearce-Kelling, S.E., Swaroop, A., Friedman, J.S., Aguirre, G.D., and Acland, G.M. (2009). Canine RD3 mutation establishes rod-cone dysplasia type 2 (rcd2) as ortholog of human and murine rd3. Mammalian Genome 20, 109–123.
M L Suber, S.J.P. (1993). Irish setter dogs affected with rod/cone dysplasia contain a nonsense mutation in the rod cGMP phosphodiesterase beta-subunit gene. Proceedings of the National Academy of Sciences of the United States of America 90, 3968–3972.