Investigation Of SLC26A4 Mutations Associated With Large Vestibular Aqueduct Syndrome And Mondini Dysplasia

Objective: The rapid development of modern medical technology including the imaging technology, genetic testing, etc, knowledge of deaf people has made substantial progress.In the inner ear malformation, Mondini dysplasia incidence rate is highest, and often accompanied by vestibular aqueduct. Mondini dysplasia characterized by abnormal development of the cochlea, no characteristic clinical manifestation, mainly sensorineural hearing loss, and sometimes accompanied by dizziness, nausea, vomiting and other symptoms of vestibular.The large vestibular aqueduct syndrome is a form of progressive hearing loss volatility, mainly congenital inner ear malformations hearing impairment, along with the development of imaging inner ear malformations were found in a disease-induced deafness. The large vestibular aqueduct syndrome is autosomal recessive genetic diseases, gene mapping in the 7q22-31.1. The large vestibular aqueduct syndrome the clinical features are not typical for the volatility of the overall decline in hearing, often in the incentive later (head trauma, breath, cold, etc.) after a sudden drop in hearing, sometimes accompanied by vestibular symptoms. The large vestibular aqueduct syndrome and the Mondini dysplasia are common, one of the inner ear malformation, at present the reason is not fully clear, and further explore Mondini dysplasia and the large vestibular aqueduct syndrome and genetic characteristic , audiological features .Efforts should be directed to minimize the delay in diagnosis at Mondini dysplasia and the large vestibular aqueduct syndrome.Methods: The topics collected 13 patient of Mondini dysplasia and the large vestibular aqueduct syndrome. Genomic DNA was exatracted from peripheral blood. All 21exons of the SLC26A4 gene were amplfied by intronic polymerase chain reaction (PCR),then thE PCR products sequenced. The sequences were analysed with BioEdit.Results: HRCT scan on temporary bones were performed to the 13 patients.11of them is large is large vestibular aqueduct syndrome.5 of them accompanied by Mondini dysplasia. The other two was the cochlear hypoplasia. The incidence in age is from birth to 6 years old. 6 of them were significant incentives prior to the hearing drop.( cold. Fall down. Head Impact. Pure-tone audiometry was performed to five patient .the air-bone gap was greater than 10dBHL.The patients present mixed hearing loss.ABR was performed to the other patient。7 ears (6 cases) recorded the ASNR in ABR testing。The latency of ASNR appeared at2.55~2.84 ms in the ABR testing. There are four people had normal gene in the test. Two cases carried homozygous SLC26A4 IVS7- 2A>G mutation.1 case had heterozygous SLC26A4 IVS7-2 A>G/1975G>C mutation.1 case had heterozygous SLC26A4 IVS7-2 A>G/2168 A>G mutation.1 case had heterozygous SLC26A4 IVS7-2 A>G/1022delC mutation.1 case had heterozygous SLC26A4 IVS7-2 A>G/ 1226 G>A mutation.1 case had heterozygous SLC26A4 IVS 4+7A>G/1595G>T mutation.1 case had heterozygous SLC26A4 1226 G>A\2168A>G mutation.Conclusion: Mondini dysplasia and the large vestibular aqueduct syndrome are frequently associated with progressive sensorineural hearing loss presenting in childhood.The patients could presentsensorineural hearing loss。CT in its diagnosis play an important role.The occurrence of acoustically evoked short latency negative responsemay indicate the diagnoses ofenlarged vestibular aqueduct.There is a high incidence of SLC26A4 IVS7-2A>G.