Inherited diseases of collagen, elastin and keratin

This article highlights the common disorders associated with inherited abnormalities of the collagen, elastin and keratin. The derrnal structural proteins (extracellular matrix proteins) comprise predominantly collagens, of which at least 19 types are known. Collagens constitute most of the dermis, and abnormalities lead to impaired wound healing illustrated by the Ehlers-Danlos syndromes. They also have a critical role at the basement membrane zone, and defects lead to loss of epidermal adhesion and blistering, resulting in certain types of epidermolysis bullosa. Pseudoxanthoma elasticum is a disorder characterized by cutaneous, ocular and cardiovascular complications and is associated with elastic fibre abnormalities. The exact function of the transmembrane transport gene (ABCC6) implicated has not yet been fully elucidated. Keratins have an integral role in the integrity of epidermal cells and their expression varies between body sites. Abnormalities lead to a wide variety of clinical phenotypes, most commonly keratoderma.