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Degenerative Myelopathy Bernese Mountain Dog Type (DM-B, SOD1 exon1)
| Acronym: | DM-B, DM2 |
| Gene: | SOD1 |
| Mutation: | c.52A>T |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Degenerative myelopathy (DM) is a genetic neurodegenerative disorder affecting the spinal cord, resulting in slowly progressive motor neuron loss and paralysis. DM was initially described in German Shepherds but has since been diagnosed in several other dog breeds, including Bernese Mountain dog, Pembroke Welsh Corgi, Boxer, Chesapeake Bay Retriever, and Rhodesian Ridgeback. The disease occurs in affected dogs in late adulthood, at approximately 8 years of age, and is characterized by a slowly progressive general proprioceptive ataxia and upper motor neuron paralysis of the pelvic limbs. The specific type of DM found in Bernese Mountain dogs is associated with a point mutation of the canine SOD1 gene that encodes a superoxide dismutase 1. Superoxide dismutase 1 is an enzyme that binds to molecules of copper and zinc to break down toxic, charged oxygen molecules called superoxide radicals that can cause severe damage to cells.
Bernese Mountain Dog type of neurodegenerative disorder is inherited as an autosomal recessive inheritance pattern with incomplete penetrance. That means dogs that carry both copies of mutated genes have a strong predisposition for developing the disease, whereas the carriers of the mutated genes are at low risk and may develop a mild and slowly progressive form of the disease. That is why early detection by genetic testing is crucial and can help identify carriers and 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:
Wininger, F. A., Zeng, R., Johnson, G. S., Katz, M. L., Johnson, G. C., Bush, W. W., Jarboe, J. M., Coates, J. R. (2011). Degenerative myelopathy in a Bernese Mountain Dog with a novel SOD1 missense mutation. Journal of veterinary internal medicine, 25(5), 1166–1170. https://doi.org/10.1111/j.1939-1676.2011.0760.x
Mataragka, A., Ikonomopoulos, J., Zervas, G. S., Vamvakidis, C. D., Tzimotoudis, N., Hager-Theodorides, A. L., Gazouli, M., Kominakis, A. (2021). Allele and genotype frequencies of the SOD1 gene polymorphism associated with canine degenerative myelopathy in Belgian Malinois dogs in Greece. Veterinary world, 14(6), 1472–1479. https://doi.org/10.14202/vetworld.2021.1472-1479