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Epidermolysis Bullosa Dystrophica
Dystrophic Epidermolysis Bullosa

  • Type VII Collagen (COL7A1)
Mutation in the COL7A1 gene causes dystrophic EB, which can be inherited in either an autosomal dominant or autosomal recessive manner. There is significant variability in the phenotype, depending on the location and type of the mutation(s) in COL7A1 gene. Sequencing of the 118 exons of the COL7A1 gene is expected to identify mutations in greater than 90% of patients with clinical and histologic features of dystrophic EB.

Blistering usually begins in the neonatal period and may continue throughout life or be transient (transient bullous dermolysis of the newborn). Blisters can be generalized and include oral and esophageal lesions in the severest form (Hallopeau-Siemens) or may be localized to the elbows and knees, and/or hands and feet in the milder forms. Dystrophic nails are often present. Although not usually lethal, in the severest cases infants may succumb to infection or other complications. The lifetime risk of squamous cell carcinoma in patients with the Hallopeau-Siemens is over 90%.

In affected individuals the tissue separation (blister) occurs below the lamina densa. Anchoring fibrils may be reduced or absent. Collagen VII staining may be reduced or absent in the more severe forms or may appear relatively normal in the milder forms. It is useful to have appropriate immunohistochemical and/or electron microscopic studies accomplished prior to beginning molecular genetic studies. GeneDx suggests that the referring physician contact Beutner Laboratories in Buffalo, NY (716-838-0549) or Peter Marinkovich at Stanford University (650-725-5196) to arrange for immunohistochemical analysis of a skin biopsy from the affected individual. If these studies are consistent with dystrophic EB, molecular analysis of the COL7A1 gene is appropriate. Sequencing can be performed on a blood sample or buccal swab from an affected individual but because of the large size of the gene, blood is preferred.

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Epidermolysis bullosa, EB, EB dystrophica, Dystrophic, Hallopeau-Siemens , Pasini , pruriginosa , pretibial form , congenital absence of skin, collagen, COL 7, COL7A1, COL7, collagen 7, type 7 collagen, blister, bullous, bullae

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