METHODS Subjects Our subjects consisted of 39 affected subjects with EVA and their unaffected relatives from 31 families. A total of 84% of these families were Caucasian. Affected individuals included 17 males and 22 females ranging in age from 2 to 59 years old. The eligibility criterion for an affected subject was EVA in at least one ear imaged by CT or MRI. EVA was defined as a vestibular aqueduct (VA) diameter exceeding 1.5 mm at the midpoint between the posterior cranial fossa and the vestibule of the inner ear, or a grossly malformed overall morphology of the VA. 1 The study was approved by the joint NINDS/NIDCD Institutional Review Board (National Institutes of Health, Bethesda, MD) and written informed consent was obtained for all subjects.

Clinical evaluation Each affected subject was evaluated at the NIH Clinical Center. This included a detailed medical history and physical examination (by SPP or AJG). Age appropriate audiometry was performed and past audiology records were reviewed when available. Urinalysis and renal ultrasound examinations were obtained in order to identify patients with renal abnormalities. Thyroid ultrasound was performed to determine presence or absence of goitre. Whenever possible, high resolution imaging of the inner ear was performed using a fast induction employing steady state excitation (FIESTA) and/or a T2 weighted, fast spin echo on a 1.5 T MRI