Genetics and characteristics
Dystrophic Epidermolysis Bullosa (DEB) is a genetic skin condition that belongs to a heterogeneous group of skin diseases characterized by the development of blisters. DEB is divided into several subtypes based on structural changes in the skin, disease findings, and the mode of inheritance. A few types of DEB have also been discovered in dogs and one of those is specific to Central Asian Shepherd dogs. Central Asian Shepherd Type is caused by a nonsense variant in the COL7A1 gene resulting in a premature stop codon and the absence of the functional protein important. The collagen protein encoded by COL7A1 plays an important role in strengthening and stabilizing the skin. Except for skin blistering, the affected dogs usually show other signs such as the fragility of the skin and mucosae, skin erosions, nail defects, granulation tissue, keratoderma, and dyspigmentation.
This type of blistering skin condition found in Central Asian Shepherd dogs is inherited as an autosomal recessive trait requiring both mutated COL7A1 genes for the disease to develop. Dogs carrying only one mutated gene will not develop the disease but may act as carriers and potentially pass the mutation to their offspring. Early genetic testing can help identify carriers of the specific mutation 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:
Niskanen, J., Dillard, K., Arumilli, M., Salmela, E., Anttila, M., Lohi, H., Hytönen, M. K. (2017). Nonsense variant in COL7A1 causes recessive dystrophic epidermolysis bullosa in Central Asian Shepherd dogs. PloS one, 12(5), e0177527. https://doi.org/10.1371/journal.pone.0177527
Nagata, M., Shimizu, H., Masunaga, T., Nishikawa, T., Nanko, H., Kariya, K., Washizu, T., Ishida, T. (1995). Dystrophic form of inherited epidermolysis bullosa in a dog (Akita Inu). The British journal of dermatology, 133(6), 1000–1003. https://doi.org/10.1111/j.1365-2133.1995.tb06942.x