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Progressive Retinal Atrophy (JPH2-PRA) - Shih Tzu Type
| Acronym: | JPH2-PRA |
| Gene: | JPH2 |
| Mutation: | g.31720642A>C |
| Inheritance: | Autosomal Recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Progressive retinal atrophy (JPH2-PRA) is a genetic eye disorder, which belongs to blinding retinal degenerative diseases. There have been described more than 20 genes in dogs that can lead to retinal defects and progressive vision deprivation, but this type is specific for Shih Tzu dogs. As other retinal disorders, JPH2-PRA is characterized by degeneration of retinal photoreceptor cells, progressive loss of vision, retinal thinning, and atrophy of the optic nerve head. The cause of the disorder is a variant in JPH2 gene which has been previously found to be expressed in several excitable cells/tissues including retina photoreceptors. Gene product of JHP2 is a protein that mediates cross talk between cell surface and intracellular ion channels and provides a structural bridge between the plasma membrane and the sarcoplasmic reticulum.
This retinal athropy disorder in Shih Tzu 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 JPH2-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:
Urkasemsin, G., Pongpanich, M., Sariya, L., Kongcharoen, A., Buddhirongawatr, R., Rungarunlert, S., Ferreira, J. N., Chetruengchai, W., Phokaew, C., Srichomthong, C., & Shotelersuk, V. (2021). Whole genome sequencing identifies a homozygous nonsense mutation in the JPH2 gene in Shih Tzu dogs with progressive retinal atrophy. Animal genetics, 52(5), 714–719. https://doi.org/10.1111/age.13118
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.