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Early-Onset Progressive Retinal Atrophy (EO-PRA)- Spanish Water Dogs
| Acronym: | EO-PRA |
| Gene: | PDE6B |
| Mutation: | c.2218-2223del |
| Inheritance: | Autosomal Recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Early-onset progressive retinal atrophy is a genetic eye disorder, which belongs to blinding retinal degenerative diseases. This recently identified type is a new form of early-onset PRA (EO-PRA) detected in Spanish Water Dogs. As other retinal disorders, EO-PRA is characterized by disturbance of dark vision, visual field defects, and abnormalities in the electroretinogram, which can progress to blindness. The cause of the disorder is a deletion in a splicing site of PDE6B gene resulting in a non-functional protein is part of a complex found in specialized light receptor cells called rods. Rods transmit visual signals from the eye to the brain specifically in low-light conditions.
This retinal athropy disorder in Spanish Water Dogs is inherited as an autosomal recessive trait, requiring two copies of the mutated gene for the disease to develop. Dogs with only one copy of the mutated gene will not develop the disease but may act as carriers and pass the mutation to their offspring. There is no cure for EO-PRA, and the only way to prevent it is early detection by genetic testing that can help breeders in selecting future mating pairs.
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:
Winkler, P. A., Ramsey, H. D., & Petersen-Jones, S. M. (2020). A novel mutation in PDE6B in Spanish Water Dogs with early-onset progressive retinal atrophy. Veterinary ophthalmology, 23(5), 792–796. https://doi.org/10.1111/vop.12792
Miyadera, K. (2012): Genetic and phenotypic variations of inherited retinal diseases in dogs: the power of within- and across-breed studies. Mamm Genome, 23: 40-61.