Abstract
Hereditary hearing loss is the most frequent cause of congenital sensorineural hearing loss (SNHL), and advances in genetic testing have revealed various phenotypes of SNHL according to each gene mutation. On the other hand, clinical examinations, such as a history of development, family history, and various kinds of auditory examinations are also required for the diagnosis of hereditary hearing loss. In this paper, we reviewed 64 patients with bilateral congenital SNHL who visited Iwate Medical University between 1997 and 2007. Genetic testing (GJB2, SLC26A and mt. A1555G mutations) revealed 11 (17.2%) patients with positive results for genetic mutation: 9 with GJB2 mutation and 2 with SLC26A4 mutation. Among these 11 patients, 5 had a negative family history. Patients with hereditary hearing loss increased from 24 patients (37.5%) diagnosed by family history to 29 patients (45.3%) diagnosed by additional genetic testing. Furthermore, audiograms were found to be symmetrical in 10 of the 11 patients (90.9%) with GJB2 or SLC26A4 mutation.
