GJB2 is the gene most frequently associated with hereditary hearing loss, and the GJB2 mutation spectrums vary among different ethnic groups. In this study, the mutation spectrum as well as clinical features of patients with GJB2 mutations as found in more than 1000 Japanese hearing loss families are summarized. The present results show that the frequency of GJB2 mutations in the Japanese population with hearing loss is 14.2% overall and 25.2% in patients with congenital hearing loss. c.235delC was the most frequent allele (49.8%), was associated with a more severe phenotype, and was mainly found in patients who were diagnosed by the age of 3. In contrast, the second most frequent was p.V37I (16.5%), which has a milder phenotype and was mainly found in patients diagnosed at a higher age. Additional clinical features in hearing loss patients with GJB2 mutations in this study were the near absence of tinnitus, vestibular dysfunction and inner ear malformations.

The mutation spectrum reviewed in this study clearly indicated that the frequent mutations in the GJB2 and SLC26A4 genes are consistent with the founder mutation hypothesis. A comparison with the Y-chromosome phylogenetic tree indicated that these mutations may have occurred during human migration.

Conclusion.3 T MRI after intratympanic injection of gadolinium-based contrast agent (GBCA) is more useful for the diagnosis of endolymphatic hydrops compared with the glycerol test and electrocochleography (ECoG).Objective:To investigate the relationship between 3 T MRI after intratympanic injection of GBCA, the glycerol test, and ECoG in patients with Meniere's disease (MD).Methods:A total of 20 patients with MD were evaluated. Diluted gadodiamide (a gadolinium-based contrast agent) was administered to the bilateral tympanic cavity by injection through the tympanic membrane. After 24 h, the endolymphatic hydrops was evaluated by a 3.0 T MR scanner. To investigate cochlear hydrops, the glycerol test and ECoG were carried out in all patients.Results:A positive result was observed in 11 patients (55%) in the glycerol test and in 12 patients (60%) by ECoG. The incidence of positive findings when evaluating the same patients with both the glycerol test and ECoG increased to 75%. Nineteen of 20 (95%) patients showed positive results for 3 T MRI.

Objectives: We sought to elucidate the gene expression profiles of the causative genes as well as the localization of the encoded proteins involved in hereditary hearing loss. Methods: Relevant articles (as of September 2014) were searched in PubMed databases, and the gene symbols of the genes reported to be associated with deafness were located on the Hereditary Hearing Loss Homepage using localization, expression, and distribution as keywords. Results: Our review of the literature allowed us to systematize the gene expression profiles for genetic deafness in the inner ear, clarifying the unique functions and specific expression patterns of these genes in the cochlea and vestibular endorgans. Conclusions:The coordinated actions of various encoded molecules are essential for the normal development and maintenance of auditory and vestibular function.

Conclusions: Our results indicated that electric acoustic stimulation (EAS) is beneficial for Japanese-speaking patients, including those with less residual hearing at lower frequencies. Comparable outcomes for the patients with less residual hearing indicated that current audiological criteria for EAS could be expanded. Successful hearing preservation results, together with the progressive nature of loss of residual hearing in these patients, mean that minimally invasive full insertion of medium/long electrodes in cochlear implantation (CI) surgery is a desirable solution. The minimally invasive concepts that have been obtained through EAS surgery are, in fact, crucial for all CI patients. Objectives: This study was conducted to evaluate hearing preservation results and speech discrimination outcomes of hearing preservation surgeries using medium/long electrodes. Methods: A total of 32 consecutive minimally invasive hearing preservation CIs (using a round window approach with deep insertion of a flexible electrode) were performed in 30 Japanese patients (two were bilateral cases), including patients with less residual hearing. Hearing preservation rates as well as speech discrimination/perception scores were investigated on a multicenter basis. Results: Postoperative evaluation after full insertion of the flexible electrodes (24 mm, 31.5 mm) showed that residual hearing was well preserved in all 32 ears. In all patients, speech discrimination and perception scores were improved postoperatively.