Screening of 12 Turkish families with apparently autosomal. recessive nonsyndromic sensorineural deafness without GJB2 and mtDNA m. 1555A > G mutations for 11 previously mapped recessive deafness loci showed a family in which hearing loss cosegregated with the DFNB9 (OTOF) locus. Three affected children were later found to carry a novel homozygous c.3032T > C (p.Leu.1011Pro) mutation in the OTOF gene. Both parents were heterozygous for the mutation. p.Leu1011Pro alters a conserved leucine residue in the C2D domain of otoferlin. Pure tone audiometry of the family showed severe to profound sensorineural hearing loss (with U-shape audiograms) in children, and normal hearing in the parents. Otoacoustic emissions and auditory brainstem response (ABR) suggested the presence of auditory neuropathy in affected individuals. (c) 2005 Wiley-Liss, Inc.