Follow-up study in a family with dominant progressive hereditary sensorineural hearing impairment. II. Clinical aspects.

An autosomal-dominant progressive sensorineural hearing loss in six generations of a large family with 105 affected members was studied. The pattern of inheritance is autosomal dominant with an almost complete penetrance. The age of onset is between 5 and 15 years. Individuals with a normal audiogram at the age of 15 and over will not develop the disorder. Different generations show an identical pattern of progression. Because the age of onset is the same, anticipation is excluded. The hearing loss is symmetrical. Over 40 years, low-frequency losses are greater in females than in males. Epistasis possibly plays a role since affected individuals in branch II of this family have a more severe expression than those in the other two affected branches. No abnormal excretion of organic acids in the urine could be established.