The dermis is a differentiated connective tissue whose mechanical properties originate in a network of polymeric macromolecules associated to a variety of glycoproteins and proteoglycans. Each macromolecule contains specific recognition domains allowing their self-association and binding to other macromolecules and to the cell membrane receptors, through. Cell function is regulated by the transfer of information resulting from contact with the polymeric network, as well as by cytokines and growth factors. The structure of the genes encoding the different macromolecules and their regulation sequences are largely known. Various connective tissue disorders are due to alterations of these genes.