Dystrophic Epidermolysis Bullosa in Central Asian Shepherd and Golder Retriever
Dystrophic epidermolysis bullosa is an inherited skin disorder affecting 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 for of EB has been described in German Shorthaired Pointer and mixed-breed dogs with junctional EB, and also in Akita Inu with dystrophic EB. Molecular background causing the disorder in named breeds is unknown.
Characteristics and Symptoms
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, 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 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.
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.