[From gene to disease; a progressive cochlear-vestibular dysfunction with onset in middle-age (DFNA9)].

DFNA9 is an autosomal dominant genetic inner-ear hearing impairment that starts to show itself in the 3rd and 4th decades of life. This hearing impairment may be of a different degree of severity in each ear. Progression of hearing loss is about 3 dB/year. In about one in three patients severe vestibular symptoms similar to those in Ménière's disease are present as a result of a progressive impairment of the vestibular system. Several mutations were found in the COCH-gene on chromosome 14. There are indications that some of the mutations disrupt the folding of the cochlin protein, an important component of the extracellular matrix in the inner ear. DNA-diagnostics confirming the diagnosis ofDFNA9 are possible.