Autosomal dominant non-syndromal low-frequency sensorineural hearing impairment linked to chromosome 4p16 (DFNA14): Statistical analysis of hearing threshold in relation to age and evaluation of vestibule-ocular functions

A Dutch kindred was studied with low-frequency sensorineural hearing impair ment linked to a new locus on chromosome 4p16 (DFNA14). Of the affected ind ividuals, 21 (aged 11-75 years) were examined and the most recent audiogram was used for cross-sectional analysis of hearing threshold in relation to age. Suitable serial audiograms were available for a longitudinal analysis in nine cases; they had been obtained from the age of six years onwards and covered a follow-up period from 14 to 36 years. The presumably congenital (offset) component of SNHI was extrapolated or estimated from average value s and offset thresholds were found of about 45 dB at 0.25-1 kHz, 25 dB at 2 kHz and 10 dB at 4-8 kHz. Significant progression in hearing impairment occurred at all frequencies, but could be attributed to presbyacusis. The combination of congenital, sta tionary low-frequency SNHI and presbyacusis resulted in an up-sloping audio gram in the first five decades of life, which evolved into a flat-type audi ogram in the sixth or seventh decade and a down-sloping audiogram at a more advanced age. With few exceptions, vestibular function was intact.