Alport's syndrome: can carriers be identified by audiometry?

Alport's syndrome is characterized by familial nephropathy with haematuria, sensorineural hearing loss and ocular abnormalities. It is transmitted as an X-linked dominant condition. In the affected males the symptoms are severe compared with females who show a more variable clinical picture due to the effect of lyonization of the X-chromosome. The diagnosis of carriers of genetic disease is extremely valuable for the purpose of counselling the patients as well as their relatives. A number of attempts have been made in the past to diagnose these carriers. Some studies have shown that it is possible to diagnose carriers of conditions where hearing loss is a symptom, by sensitive audiometric techniques. In this study we examined obligate and possible carriers of Alport's syndrome with pure-tone audiometry (PTA) and the audioscan method. We found that all obligate carriers and a predictable proportion of possible carriers had either a hearing loss on PTA or a mid frequency notch in the audioscan.