[Hope for new therapies of severe genetic skin diseases].

The skin barrier is composed of a thin horny layer, which prevents water loss and intrusion of noxious factors, and a thicker, viable layer of epidermis, which is strongly attached to the underlying dermis. Serious impairment of the skin barrier may result from genetic diseases interfering with the attachment and/or terminal differentiation of keratinocytes. In epidermolysis bullosa, defects in the anchoring proteins of epidermis cause neonatal blistering and a life-long problem with widespread skin erosions. In congenital ichthyosis, various enzyme deficiencies (transglutaminase 1, steroid sulfatase, etc) or mutations in structural proteins (cytokeratins, plakophilin, etc) cause massive hyperkeratosis and/or inflammation resulting in chronic problems with the skin barrier. Our increasing knowledge of the etiology of these diseases has already facilitated diagnosis and genetic counseling. Hopefully this knowledge will also pave the way for new remedies, including cutaneous gene therapy for the most severe conditions.