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Stargardt disease (STGD) - Labrador Retriever Type
| Acronym: | STGD |
| Gene: | ABCA4 |
| Mutation: | c.4176dup |
| Inheritance: | Autosomal Recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Stargardt disease (STGD) is a genetic eye disorder that is part of a larger group of blinding retinal degenerative diseases along with the most common eye disorder in dogs, progressive retinal atrophy (PRA). Inherited retinal dystrophies are a genetically and clinically heterogeneous group of eye diseases leading to severe visual impairment in both humans and dogs and all have been similarly characterized by degeneration of retinal photoreceptor cells, progressive loss of vision, retinal thinning, and atrophy of the optic nerve head. A novel form of retinal degeneration has been reported in Labrador retriever dogs and it is caused by a loss-of-function mutation in the ABCA4 gene, retina specific member of the ATP-binding cassette transporter superfamily. The gene product of ABCA4 is a protein that has an important role during the process in which light enters the eye and is converted into electrical signals that are transmitted to the brain.
STGD in Labrador Retriever 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 STGD, 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:
Mäkeläinen, S., Gòdia, M., Hellsand, M., Viluma, A., Hahn, D., Makdoumi, K., Zeiss, C. J., Mellersh, C., Ricketts, S. L., Narfström, K., Hallböök, F., Ekesten, B., Andersson, G., & Bergström, T. F. (2019). An ABCA4 loss-of-function mutation causes a canine form of Stargardt disease. PLoS genetics, 15(3), e1007873. https://doi.org/10.1371/journal.pgen.1007873
Zangerl, B., Lindauer, S. J., Acland, G. M., & Aguirre, G. D. (2010). Identification of genetic variation and haplotype structure of the canine ABCA4 gene for retinal disease association studies. Molecular genetics and genomics : MGG, 284(4), 243–250. https://doi.org/10.1007/s00438-010-0560-5