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Dystrophic Epidermolysis Bullosa (DEB) - Golden Retriever Type
| Acronym: | EB, DEB, RDEB |
| Gene: | COL7A1 |
| Mutation: | c.5716G>A |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Dystrophic epidermolysis bullosa is an inherited skin disorder affecting the Central Asian Shepherd and Golder Retriever breed, The disorder causes blistering in the skin and the mucosal membranes, but is not associated with severe deformities. Dystrophic epidermolysis bullosa is a part of mechanobullous groups of disorders, which are characterized as hereditary noninflammatory skin diseases in which bullae (elevated lesions of the skin which contain fluid) and erosions result from slight mechanical trauma. There have been several causative genes of epidermolysis bullosa identified in dogs and humans, each causing type of EB specific in its symptoms or mode of inheritance. Different forms of EB have been described in German Shorthaired Pointer and mixed-breed dogs with junctional EB, and also in Akita Inu with dystrophic EB. The molecular background causing the disorder in named breeds is unknown.
The disorder’s symptoms are recognizable soon after the puppies’ birth. Puppies report having multiple vesicles, bullae, and ulcers in the oral and oropharyngeal mucosa, inner pinnae, the dorsal plane of the nose, ventral abdomen, external genital, and footpads. Histological examination shows separation at the dermal-epidermal junction with cleft formation. In the larger clefts numerous mononuclear cells, neutrophils, necrotic debris, and erythrocytes are detected, suggesting an inflammation. No histological changes were detected in the brain, the respiratory and gastrointestinal tract, heart, liver, spleen, pancreas, and other glands.
Dystrophic Epidermolysis Bullosa in Central Asian Shepherd and Golden Retrievers is caused by a mutation in the COL7A1 gene. This mutation results in a premature stop codon and an early truncation of the COL7A1 protein. COL7A1 gene encodes for collagen type VII, which functions as an anchoring fibril between the external epithelia and the underlying stroma. Mutations in the collagen type VII cause the abnormal synthesis of the anchoring fibril and intradermal splitting of the dermal-epidermal junction. Dystrophic Epidermolysis Bullosa in Central Asian Shepherds and Golden Retrievers is inherited in an autosomal recessive pattern. A dog can be clear, carrier or affected. Carriers of the gene are heterozygous and do not develop the disease’s symptoms. When mating two carrier dogs, each future cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
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:
Baldeschi C, Gache Y, Rattenholl A, Bouillé P, Danos O, Ortonne JP, Bruckner-Tuderman L, Meneguzzi G. Genetic correction of canine dystrophic epidermolysis bullosa mediated by retroviral vectors. Hum Mol Genet. 1;12(15):1897-1905, 2003.
Niskanen J, Dillard K, Arumilli M, Salmela E, Anttila M, Lohi H, et al. (2017) Nonsense variant in COL7A1 causes recessive dystrophic epidermolysis bullosa in Central Asian Shepherd dogs. PLoS ONE 12(5): e0177527.