[Difference of SLC26A4 gene mutation frequency between patients with large vestibular aqueduct syndrome and/or Mondini dysplasia].

Objective:The purpose of this study was to evaluate the mutation frequency of SLC26A4 gene in patients with enlarged vestibular aqueduct syndrome（EVAS） and/or Mondini dysplasia（MD）, so as to provide evidence for molecular diagnosis of deafness. Methods:In total, 74 patients with sensorineural hearing loss were included in this study. All patients underwent thin-layer CT examination of temporal bone. The coding exons of SLC26A4 were analyzed by second-generation sequencing in all subjects. Results:Among them, 37 patients with EVAS and MD（E+M group）, 28 patients with EVAS and without MD（E group）, and 9 patients with isolated MD（M group） were identified. In 74 cases, 66 cases（89.2%） were found to have mutation, including 64 cases（86.5%） of biallelic mutation and two cases（2.7%） of single allele mutation. The detection rate of SLC26A4 in different groups was statistically significant（P<0.001）. The mutation rate in group M was significantly lower than that in Group E and E+M（P<0.001）. In Group E, 27 cases（96.4%） had SLC26A4 biallelic mutations and one case（3.6%） had SLC26A4 single allele mutation, respectively; in Group E+M, 37 cases（100%） had SLC26A4 biallelic mutations; in group M, only one patient（11.1%） carried monoallelic mutations of the SLC26A4 gene. Conclusion:There are totally different pathogenesis in Chinese EVAS patients with or without MD, or isolated MD. Early clinical genetic diagnosis of patients with EVAS and/or MD helps to provide accurate information about the genetic causes of hearing loss, provide genetic counseling, and implement appropriate disease control and prevention measures. Next generation sequencing technology plays an increasingly important role in molecular diagnosis of deafness.