Hearing loss and pigmentary disturbances in Waardenburg syndrome with reference to WS type II.

Thirty families in which there were 149 individuals affected by the Waardenburg syndrome (WS) were investigated for penetrance of hearing loss and pigmentary abnormalities. Twenty two families contained 89 individuals affected by WS Type II and eight families with 60 individuals affected by Type I. A bilateral symmetrical sensorineural hearing loss was found to be the most common type of hearing loss. The most frequent degree of hearing loss category was a hearing loss of > 100dB HL with no difference between syndrome types. Although there was no significant difference in the frequency of pigmentation disorders between Type I and II, considering these abnormalities as a whole, heterochromia irides was more common in Type II than Type I and other pigmentation disorders were more frequent in Type I: 62 per cent of Type I patients had more than one pigmentary defect, but only 28 per cent of Type II. Pigmentary disturbances were not significantly more frequent in the hearing impaired group than in the normally hearing group in either Type I or II when taking into account the occurrence of only one pigmentation disorder. There was a significantly higher proportion of pigmentary defects in the hearing impaired group with Type I when only those having more than one pigmentary abnormality were compared: 93.3 per cent of Type I patients and 88.5 per cent of Type II patients with a profound hearing loss had pigmentary defects. The frequency of pigmentation disorders was not greater when the hearing loss was more severe in either type. Penetrance for hearing loss and pigmentary abnormalities showed marked intrafamilial and interfamilial variation.