Epidermolysis bullosa: a spectrum of clinical phenotypes explained by molecular heterogeneity.

Great progress has recently been made in understanding the molecular basis of various heritable skin diseases. A prototype of such conditions is epidermolysis bullosa (EB), a heterogeneous group of mechano-bullous disorders characterized by fragility of the skin and other specialized epithelia. Blistering of the skin in EB results either from fragility of epidermal cells or from defective attachment of the epidermis to the underlying dermis, because of genetic lesions within molecules of the basement-membrane zone at the dermal-epidermal junction. Distinct mutations have been discovered in ten different genes encoding the structural components within this layer. The combinations and the types of mutations, as well as their positions in the altered gene products, collectively reflect the phenotypic variability observed in this group of heritable skin diseases.