Phenotypic characterization of a DFNA6 family showing progressive low-frequency sensorineural hearing impairment

Only three autosomal dominant hearing loss loci (DFNA1, DFNA6/14/38 and DFNA54) have been reported to be associated with predominantly low-frequency (<2kHz) sensorineural hearing impairment (LFSNHI). The DFNA6 locus was previously mapped to chromosome 4p16.3. It was showed that WFS1 is located in this region. This study presents a six-generation family from Hungary with nonsyndromic, post-lingual, bilateral, symmetric, progressive LFSNHI, that discloses positive linkage to the DFNA6 region. Eleven genetically affected family members have LFSNHI. The HI is started before the age of 25 years. The severity of HI varies from mild to moderate, related to age. Progression was mild but significant at all frequencies causing a flat type audiogram. High-resolution temporal bone CT scan showed normal external, middle and inner ear without any osseus malformations in the temporal bone. Studying genotype-phenotype correlations will enhance our understanding of normal and disturbed hearing process.