Common Deafness Gene Characteristics Research Of Patients With Nonsyndromic Hearing Loss In Tibetan, Tu Nationality And Mongolian In The Northwest Of China

Deafness affects patients’daily communication and access to information, and influences human physical and mental health and the quality of life. Studies have found that the causes of deafness including genetic factors and environmental factors. About60%deafness people are caused by genetic defects. Genes related to deafness were about140, but the majority patients with deafness was caused by a handful of single gene defects. Nationwide deaf disease molecular epidemiology survey data shows that GJB2, SLC26A4and mtDNA (A1555G and C1494T) mutations were three most common deafness genes in hereditary deafness. But the detection rates of different regions and different ethnic groups were obvious different. At present studies in China’s northwest ethnic minorities, especially Tibetan, Tu nationality and Mongolian are rare. The aim of this study is to research common deafness gene mutation characteristics in189cases of Tibetan, Tu nationality and Mongolian NSHI patients from Gansu and Qinghai province. We can preliminary understand the hereditary deafness etiology characteristics in this region, and provide a scientific basis for disease gene diagnosis and genetic counselingIn this study, we collected189Tibetan, Tu nationality and Mongolian NSHI patient’s data and peripheral blood. We extract DNA from peripheral blood. PCR and direct sequencing were used to analyze the coding region of GJB2, mtDNA and exons8and18of SLC26A4gene. The disease causative mutations were detected in Tibetan and Tu nationality patients whereas the GJB2mutations were not detected in Mongolian cases in present work due to the selection effect of low sample coverage. The mutant allele rate of GJB2gene is5.8%(14/242) in Tibetan, of which c.235delC is the most prevalent mutation. Four other kinds of pathogenic mutations were detected in Tibetan patients:c.94C<T, c.257C<G, c.299-300delAT and c.504insAACG. The mutant allele rate of GJB2gene is11.22%(11/98) in Tu nationality patients. Two kinds of mutations were detected:c.235delC and c.176-191de116. c.235de1C is the hot spot of GJB2mutations in Tibetan and Tu nationality, which indicates that235delC is the most common forms of GJB2mutation in Chinese people. We have identified that3.3%(4/121) Tibetan patients and10.2%(5/49) Tu nationality patients were caused by GJB2gene mutations. There was no significant difference between Tibetan and Tu nationality in mutant allele rate of GJB2gene. The c.235delC carry rate of Tu nationality was higher than Tibetan.Mutant allele frequency of SLC26A4in Tibetan, Tu nationality and Mongolian were4.54%,6.12%and15.79%respectively, c.919-2A>G was the most common mutation of the SLC24A4gene, which is consistent with other domestic research results concerning the SLC26A4gene.5%Tibetan,6.12%Tu nationality and15.79%Mongolian patients were caused by SLC26A4gene mutations. Statistical analysis showed that mutant allele frequency of SLC26A4and c.919-2A>G carry rate were highest in Mongolian, next in Tu nationality, minimum in Tibetan. The mutation frequency of mtDNA12SrRNA in Tibetan, Tu nationality and Mongolian deaf populations was5.79%,10.2%and5.26%. There was no significant difference between Tibetan, Tu nationality and Mongolian in mutation frequency of mtDNA12SrRNA.In conclusion, the mutation of GJB2gene, SLC26A4gene and mtDNA gene among Tibetan, Tu nationality and Mongolian in northwest of China are high. Common deafness gene screening helps us with the progress of the gene diagnosis and genetic counseling in the three minority nationalities in our region.