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目的为建立母系遗传性聋的基因诊断方法,从分子水平探讨其发病机理。方法收集母系遗传性聋2个家系(31名个体)和健康中国人对照组100例的外周血,提取DNA。PCR扩增mtDNA目的片段,分别以Alw261、Apal、XbaI、Bbv1限制性内切酶检测1555G、3243G、7445G、7598A点突变;行mtDNA12SrRNA、tRNAleu(UUR)、tRNASer(UCN)、COⅡ基因测序。Bbv1酶切检测100个白种人7598A点突变作为另一组对照。结果D家系的7个患者和E家系的6个患者以及他们的母系后代和2例正常中国人COⅡ基因片段有一个7684T→C(Leu33Leu)同义突变。D家系的7个患者以及母系后代和100例正常中国人对照组中2人有7598G→A(Ala5Thr)错义突变,D家系患者的配偶、E家系和100例正常白种人均未发现7598G→A点突变。所有被检对象1555G、3243G、7445G点突变均为阴性。结论7684T→C(Leu33Leu),7598G→A(Ala5Thr)是2个新的线粒体基因的多态性改变,很可能还有其它线粒体点突变与母系遗传性聋有关。
Objective To establish genetic diagnosis of maternal hereditary deafness and to explore its pathogenesis at the molecular level. Methods Peripheral blood samples of 100 maternal hereditary deafness (31 individuals) and healthy Chinese controls were collected and DNA was extracted. The mtDNA fragments were amplified by PCR. The 1555G, 3243G, 7445G and 7598A point mutations were detected by Alw261, Apal, XbaI and Bbv1 restriction endonucleases respectively. The mtDNA12SrRNA, tRNAleu (UUR), tRNASer (UCN) and COII were sequenced. Bbv1 digestion detected 100 Caucasian 7598A point mutations as another group of controls. Results There were 7684T → C (Leu33Leu) synonymous mutations in 7 patients in D family and 6 patients in E family as well as in their maternal offspring and 2 normal Chinese COⅡ gene fragments. There were 7598G → A (Ala5Thr) missense mutations in 7 patients in D family, 2 in maternal offspring and 100 normal Chinese controls, 7598G → A (Ala5Thr) in spouse, E family and 100 normal Caucasian individuals in D family A point mutation. All subjects were 1555G, 3243G, 7445G point mutations were negative. Conclusions 7684T → C (Leu33Leu) and 7598G → A (Ala5Thr) are polymorphisms of two new mitochondrial genes. It is possible that other mitochondrial point mutations are associated with maternal hereditary deafness.