Intraepidermal type VII collagen. Evidence for abnormal intracytoplasmic processing of a major basement membrane protein in rare patients with dominant and possibly localized recessive forms of dystrophic epidermolysis bullosa.

Of 84 patients with dystrophic forms of epidermolysis bullosa consecutively enrolled in the National Epidermolysis Bullosa Registry, four were noted by indirect immunofluorescence with the LH 7:2 monoclonal antibody to have granular basilar keratinocyte intracytoplasmic deposits, rather than exclusively linear basement membrane deposits, of type VII collagen. Indirect immunoelectron microscopy demonstrated that these deposits were primarily perinuclear, although lesser amounts were also detectable between tonofibril bundles, within hemidesmosomes, and within and beneath the lamina densa. In two patients the mode of transmission was autosomal dominant; in two others the inheritance pattern was unknown. Whereas widespread lesions were present at birth, in each case blistering ceased within the first year of life, reminiscent of the findings in transient bullous dermolysis of the newborn. We interpret these laboratory findings as indicative of the presence of a defect in the intracytoplasmic packaging or in the transport of type VII collagen within basilar keratinocytes.