Significant progress has recently been made in understanding the molecular basis of heritable skin diseases, such as epidermolysis bullosa, a group of mechano-bullous genodermatoses. In particular, the dystrophic forms of epidermolysis bullosa have been shown to result from distinct mutations in the gene encoding type VII collagen, the major, if not the exclusive, component of the anchoring fibrils. These mutations result in deficient synthesis and/or altered assembly of the anchoring fibrils, thus compromising the integrity of the cutaneous basement membrane zone. The mutations in the type VII collagen gene have implications for understanding the structure-function relationships of the type VII collagen molecule, and also provide the basis for prenatal DNA-based diagnosis in families at risk for recurrence of the disease. Finally, understanding the genetic basis of dystrophic forms of EB sets the stage for gene therapy approaches for the treatment of these devastating skin diseases.