Waardenburg syndrome

Waardenburg syndrome is a group of rare genetic conditions in which some degree of congenital hearing loss occurs together with deficiencies of pigmentation. Pigment changes can include strikingly pale blue eyes, one blue and one brown eye, a white forelock or patches of light skin. Four main types are recognised: type 2 shows these basic features, type 1 adds widely spaced inner eye corners, type 3 adds malformed arms and hands, and type 4 is accompanied by Hirschsprung disease. The condition arises from mutations in several genes that govern how neural crest cells divide and migrate in the embryo; PAX3, MITF and SOX10 are the genes most often involved, and most types are inherited in an autosomal dominant way. Prevalence is estimated at about 1 in 42,000. It is named for the Dutch ophthalmologist and geneticist Petrus Johannes Waardenburg, who described it in 1951.