Phenotypic discriminants in the Waardenburg syndrome

The gene for Waardenburg syndrome (WS) has been assigned to the locus 2q37 and further molecular investigations of affected families are now urgently required to explore the question of possible genetic heterogeneity. Firm positive or negative diagnosis in family members is crucial for studies of this type, but great variation in phenotypic expression sometimes makes this a difficult matter. Ethnic variation in craniofacial anatomical relationships further complicates the issue. We have attempted to establish diagnostic criteria for WS on the basis of an analysis of the phenotypes in 68 affected children who have been examined in special schools for the deaf in Southern Africa during the past 18 years. We then used these criteria for diagnostic evaluation of all available persons in seven multigeneration WS families in the Cape, as a preliminary to molecular investigations. With very few exceptions this approach permitted firm positive or negative diagnosis in these individuals.