Clinical features of female heterozygotes in the X-linked mixed deafness syndrome (with perilymphatic gusher during stapes surgery).

A new pedigree with 9 obligate and 10 probable female carriers of the X-linked mixed deafness syndrome is presented. In the male the syndrome is characterized by a perilymphatic gusher during stapes surgery, a severe progressive mixed hearing loss and lack or strong reduction of vestibular responses. Four of the 9 obligate heterozygote females show similar but much milder audiological abnormalities. The other five obligate female carriers have a normal audiogram. None of the obligate female carriers showed vestibular abnormalities such as observed in the affected males. Ten females, sisters of affected males, have a chance of 50% to be heterozygote carriers. Five of these females have also a hearing loss, the other 5 have normal audiograms. The relevance of these findings for genetic counseling and for identification of affected males is discussed.