NONSYNDROMIC HEARING-LOSS - AN ANALYSIS OF AUDIOGRAMS

We examined features of the audiograms of 136 individuals, from 28 fam ilies, affected by nonsyndromic genetic hearing loss. There were 83 (1 2 families) with autosomal dominant (AD) loss, 50 (15 families) with a utosomal recessive (AR) loss, and 3 (1 family) with X-linked recessive loss. The main audiogram shapes found were sloping (50.3%), residual (26.5%), and flat (21.0%). Specific shapes (ascending and U-shaped) on ly occurred in 3.7% of AD cases. Audiogram shapes were found to be sig nificantly different between AD and AR families, and showed intrafamil ial and interfamilial variability. In the AR group, the main shapes we re residual and sharply sloping, and in the AD group, sharply sloping, flat, and gently sloping. There was a significant difference in the d egree of hearing loss between AD and AR types, with AD being milder th an AR. It has been shown that there is more marked intrafamilial varia tion in the degree of hearing loss in AD families than in AR ones. The results suggest that the audiograms of nonsyndromic hearing loss are usually nonspecific and that counseling of family members would be bet ter based on the specific family's condition rather than on group info rmation.