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Dominant Cystinuria (D-CYS) – Miniature Pinscher Type
| Acronym: | AD Cystinuria, D-CYS |
| Gene: | SLC7A9 |
| Mutation: | c.964G>A |
| Inheritance: | Autosomal dominant |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Dominant Cystinuria is a genetic metabolic disorder characterized by excessive amounts of undissolved cystine in the urine, as well as three amino acids: arginine, lysine, and ornithine, collectively known as COLA. The low solubility of cystine in acidic and neutral urine may lead to the formation of cystine crystals which can result in urinary obstruction and renal failure. Cystinuria has been reported in more than 70 dog breeds and is usually connected to variants in two important genes, SLC3A1 and SLC7A9, that encode the basic amino acid transporter system. The type II-B of cystinuria that is found in Miniature Pinscher dogs is a consequence of a single base change in the SLC7A9 gene.
This inborn error of metabolism in dogs is inherited as an autosomal dominant trait meaning even dogs with only one mutated gene will develop the disease, not only dogs that carry two mutated genes. For dominantly inherited traits, carrying both mutated genes for the disease is usually lethal, but that is not the case with cystinuria even though it may cause more severe forms of the disease. Early genetic testing can help identify dogs that carry the gene with the specific mutation and prevent their further breeding by proper selection of 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. |
AFFECTED HETEROZYGOTE |
Tested mutation was detected in animal with „affected heterozygote“ result. Animal tested as affected heterozygote has one wild-type and one mutation allele, it is in heterozygous state. It is likely to 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.
**Penetrance of tested mutation, and potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Brons, A. K., Henthorn, P. S., Raj, K., Fitzgerald, C. A., Liu, J., Sewell, A. C., Giger, U. (2013). SLC3A1 and SLC7A9 mutations in autosomal recessive or dominant canine cystinuria: a new classification system. Journal of veterinary internal medicine, 27(6), 1400–1408. https://doi.org/10.1111/jvim.12176
Brons, A. K., Henthorn, P. S., Raj, K., Fitzgerald, C. A., Liu, J., Sewell, A. C., Giger, U. (2013). SLC3A1 and SLC7A9 mutations in autosomal recessive or dominant canine cystinuria: a new classification system. Journal of veterinary internal medicine, 27(6), 1400–1408. https://doi.org/10.1111/jvim.12176