[Hereditary epidermolysis bullosa: towards classification and genetic counseling based upon identification of molecular defects].

Inherited epidermolysis bullosa (EB) includes three main types depending on the precise ultrastructural level at which the split responsible for the blistering occurs; 1) simplex EB (SEB) located at the level of the basal cells; 2) junctional EB (JEB) located in the lamina lucida; 3) dystrophic EB (DEB) located in the dermis below the lamina densa at the level of the anchoring fibrils. The authors review the major recent progresses which have led to the identification of the genes and of several molecular defects in these three types, such as: mutations of the genes of keratins 5 and 14 in SEB, molecular defects in the gamma 2 chain gene of nicein/kalinin coding for the anchoring fibrils in JEB, abnormalities of the collagen VII gene coding for the anchoring fibrils in DEB. These data allow to consider a classification of EB based on molecular defects. They also have important consequences for genetic counselling and prenatal diagnosis for the families presenting an affected child.