Anchoring Fibrils and Type VII collagen are Absent From Skin in Severe Recessive Dystrophic Epidermolysis Bullosa

Skin of patients with severe generalized recessive dystrophic epidermolysis bullosa (SGRDEB) was studied by immunoelectron microscopy and immunoblotting with antibodies to type VII collagen, a major structural component of anchoring fibrils. In normal skin, the protein was localized to the dermoepidermal junction zone below the basement membrance and was extractable from the papillary dermis after artifical epidermolysis. In SGRDEB skin, neither immunoreactive material below the basement membrance nor identifiable anchoring fibrils could be recognized and neither the tissue from nor the specific proteolytic fragments of type VII collagen were found in extracts of SGRDEB skin. Very low amounts of type VII collagen α-chains could be detected in cultures of SGRDEB-fibroblasts, whereas normal fibroblasts synthesized more of this collagen. These results suggest that a genetic defect in the correct synthesis, secretion, or in the molecular assembly of type VII collagen may underline SGRDEB.