Heterogeneity of dominant high-frequency sensorineural deafness

There are several types of autosomal dominantly inherited sensorineural hearing loss (AD-SNHL), differentiated by audiograms. It is generally accepted that there are similarities in audiograms among members of the same family with dominant deafness. It has been supposed that AD-SNHL must be divided into several types according to their audiograms or clinical courses. Eighteen families with AD-SNHL are dealt with in this study. By measuring the slope of audiograms and superimposing audiograms, AD high-frequency sensorineural hearing loss can be divided into four types. The first type has the steepest audiograms, the second has somewhat less steep audiograms, the third has gently sloping audiograms, and the fourth has audiograms close to horizontal. In each type "The audiograms breed true", i.e. the audiograms even of members of different families having the same type do not overlap within the limits of error in audiometry. These four types of dominant high-frequency sensorineural deafness appear to be discrete clinical entities.