Absent expression of collagen XVII (BPAG2, BP180) in canine familial localized junctional epidermolysis bullosa.

Abstract

Hereditary junctional epidermolysis bullosa (JEB) represents a subset of mechanobullous diseases associated with defective hemidesmosome/anchoring filament proteins leading to cleavage in the lamina lucida of the epidermal basement membrane. In humans, most cases of JEB have been related to a deficiency of either laminin-5, collagen XVII (BPAG2, BP180) or integrin β4. We describe the existence of a previously unreported form of familial localized non-lethal JEB in German Shorthaired Pointer littermates. Acral, auricular and oral erosions and ulcers were observed. Severe ulceration of the footpads was present. Skin biopsy specimens of non-lesional and lesional skin of affected dogs were screened for a defect in basement membrane proteins using indirect immunofluorescence and immunoperoxidase testing. Epidermal staining for laminin-5 and integrin α6β4 was similar in affected and normal control dogs. Lack of expression of collagen XVII was uniquely identified in all sections of JEB probands compared with normal control dogs. The defective expression of collagen XVII is likely to be caused by mutation(s) of the COL17A1 gene, as previously reported in humans. This is, to date, the first report of a deficient basement membrane protein in canine JEB.