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目的 探讨母系遗传非综合征型耳聋发病机理及 744 5 G点突变在这类家系及散发感音神经性耳聋病例中的发生率 ,为建立相应的基因诊断方法提供依据。方法 收集两个母系遗传非综合征型耳聋家系和 14个感音神经性耳聋散发病例 ;抽外周血标本 ,从白细胞中提取 DNA;聚合酶链反应扩增线粒体DNA(mitochondrial DNA,mt DNA)目的片段 ,分别以 Alw2 6 、Apa 及 Xba 限制性内切酶检测15 5 5 G、32 43G及 744 5 G点突变 ;行 mt DNA 12 S r RNA、t RNAL eu(UUR) 、t RNASer(UCN) 基因测序。结果 经酶切检测 ,两家系中 12例为 744 5 G点突变阳性 ,其余 6例及 14例散发病例均为阴性 ,所有病例 15 5 5 G、32 43G点突变均阴性 ;744 5 G点突变呈母系遗传。mt DNA测序显示 ,所有病例 15 5 5 G、32 43G点突变均阴性 ;酶切显示为 744 5 G突变阳性病例经基因测序均发现有 (nt) 744 5 A→ G替换。结论 744 5 G点突变在母系遗传非综合征型耳聋家系中有较高的发生率 ,而在散发病例中发生率很低 ;744 5 G 结合 15 5 5 G点突变筛查对这类耳聋的诊断有重要意义。
Objective To explore the pathogenesis of maternal hereditary non-syndromic deafness and the frequency of 744 5 G mutation in cases of such family-related and sensorineural deafness, and to provide basis for the establishment of gene diagnosis methods. Methods Two maternal genotype non-syndromic deafness families and 14 cases of sensorineural deafness were collected. Peripheral blood samples were collected to extract DNA from white blood cells. PCR was used to amplify mitochondrial DNA (mt DNA) (UUR) and tRNASer (UCN) were detected by using restriction endonucleases Alw2 6, Apa and Xba respectively. Gene Sequencing. Results The results of enzyme digestion showed that 12 out of 12 cases were positive for 744 G mutation and the other 6 cases were negative and 14 cases were sporadic. All the cases were negative for 15 55 G and 32 43G point mutation. 744 5 G point mutation Was maternal genetic. The results of mt DNA sequencing showed that 1555G and 3243G point mutations were all negative in all cases. The positive results of 744 5G mutation showed that (nt) 744 5 A → G was replaced by gene sequencing. Conclusion The 744 G mutation has a high incidence in matrilineal nonsyndromic deafness pedigrees and a very low incidence in sporadic cases; 744 5 G combined with 15 55 G point mutations screening for such deafness Diagnosis is important.