alpha-crystallins consist of three gene products, alphaA, alphaB and alphaC-crystallin, which are members of the small heat shock protein family (HSP 20). They are induced by heat shock, and act as molecular chaperones by holding denatured proteins in large soluble aggregates. However, unlike other molecular chaperones, alpha-crystallins do not renature these proteins. Expression of alphaA-crystallin is restricted to the lens. Defects in this gene cause autosomal dominant congenital cataracts (ADCC). The human alphaB-crystallin gene product is expressed in many tissues, including lens, heart and skeletal muscle. Elevated expression of alphaB-crystallin is associated with many neurological diseases, and a missense mutation in this gene has co-segregated in a family with a Desmin-related myopathy.