Genetic heterogeneity in the Waardenburg syndrome.

Waardenbury syndrome is divided into three groups: Type I, with dystopia; Type II, and "pseudo-Waardenburg" syndrome, without dystopia; the third has unilateral congenital ptosis. Using Waardenburg's original variables a, b and c, ratios a/b and c/a, Cotterman's L function, newly described indices X and Y and some phenotypic manifestations, a confident neat separation of each type can be obtained. New cases of all types and electron micrographs of the hair pigment anomaly are described.