ABSTRACT
Numerous different genes may cause severe non-syndromic deafness, and a precise molecular diagnosis is particularly helpful for genetic counselling when both parents are deaf. Diagnostic assessment will include audiograms of parents as well as the child, urinalysis and Imaging can be very helpful in determining the underlying cause, with structural anomalies giving clues as to genetic or non–genetic factors. Environmental causes include rubella and thalidomide embryopathies, and — usually only in fatal cases — the ‘Potter facies’ resulting from oligohydramnios secondary to renal agenesis or other causes. Isolated external ear abnormalities, particularly when unilateral, carry a low recurrence risk, but a careful examination should be carried out for minor audiological or branchial arch defects on both sides. A few familial aggregations of Meniere’s disease have been recorded, suggesting either autosomal dominant inheritance with reduced penetrance or multifactorial aetiology.
