- A novel DFNA9 mutation in the vWFA2 domain of COCH alters a conserved cysteine residue and intrachain disulfide bond formation resulting in progressive hearing loss and site-specific vestibular and central oculomotor dysfunction. Street, V.A., Kallman, J.C., Robertson, N.G., Kuo, S.F., Morton, C.C., Phillips, J.O. Am. J. Med. Genet. A (2005)