The Waardenburg syndrome in deaf children in southern Africa.

Eighty-nine children with the Waardenburg syndrome were identified during diagnostic surveys of 3006 deaf children attending 19 special schools in southern Africa. Since a hearing deficit is present in only a minority of persons with the Waardenburg syndrome, it can be estimated that there are several thousand individuals with the faulty gene among the local population. The syndrome was encountered in deaf children of White, Black and mixed ancestry but not in Indian scholars. There were marked discrepancies in prevalence in different tribal groups. In several sets of deaf siblings, one individual had the classic syndromic stigmata while the other had apparently undifferentiated perceptive deafness. On this basis it is possible that phenotypic expression of the Waardenburg gene in some persons may be limited to a hearing deficit. Our observations indicate that the sole manifestation of the faulty gene can be irides of a uniform, striking and unusual blue colour, with or without congenital deafness.