线粒体DNA变异与2型糖尿病易感性的关联研究

目的研究湖北地区2型糖尿病（type 2 diabetes mellitus，T2DM）中线粒体基因突变的发生率及其相关性。方法采用聚合酶链反应一限制性片段长度多态性及DNA测序技术，对184例2型糖尿病患者和210名糖耐量正常的健康对照进行检测，并用mfold和tRNAscan-SE软件对检出的突变位点进行二级结构分析。结果MIND1 3316（G→A）、MIND1 3394（T→C）、D环区16189（T→C）变异率分别为3．26％、2．72％、36．9％，并首次在T2DM中发现4例MTTE14693（A→G）突变（2．17％）；对照组检出3316（G→A）突变2例（0．99％）、16189（T→C）变异56例（26．6％），朱检出3394、14693的点突变；两组间3394（T→C）、14693（A→G）、16189（T→C）变异率差别均有统计学意义（P〈0．05）；且T2DM组中16189（T→C）变异阳性者的胰岛素抵抗指数（HOMA→IR）值较16189（T→C）变异阴性组升高，差异有统计学意义（P=0．028）：多元回归分析显示该变异为参与HOMA→IR的独立变量（R2=0．043，P=0．037）。RNA二级结构预测发现，3394（T→C）和14693（A→G）突变使其相应的二级结构发生变化。结论3394（T→C）、14693（A→G）突变与T2DM的易感性有一定关联，16189（T→C）变异与湖北地区汉族人T2DM胰岛素抵抗相关。

Association of mitochondrial DNA variation with type 2 diabetes mellitus

OBJECTIVE: To explore the prevalence of mitochondrial DNA (mtDNA) mutations in patients with type 2 diabetes mellitus in Hubei. METHODS: A total of 184 cases of type 2 diabetes mellitus and 210 matched healthy controls with normal glucose tolerance were recruited for the study. The variants of mtDNA, including MIND13316 (G-->A), MIND13394 (T-->C), MTTE14693 (A-->G), MTTL1 3243 (A-->G), MTRNA1310 (C-->T) and 16189 (T-->C), were screened using PCR-restriction fragment length polymorphism (PCR-RFLP) analysis and DNA sequencing. The mutations were analyzed by mfold or tRNAscan-SE softwares. RESULTS: The mutation rates of 3316 (G-->A), 3394 (T-->C), 14693 (A-->G) were 3.26%, 2.72% and 2.17% respectively in type 2 diabetes group, whereas in the control group, the point mutations of 3394 (T-->C) and 14693 (A-->G) were not detected, but two subjects with 3316 (G-->A) were found (0.99%). There were significant differences in mutation rates of 3394 (T-->C) and 14693 (A-->G) between the two groups (P<0.05). In 4 of 184 cases, a T to C transition at nucleotide position 14693 was uncovered for the first time. The prevalence of 16189 variant among type 2 diabetes was significantly higher that of the controls (36.9% vs 26.6%, P=0.03). Moreover, the type 2 diabetes with 16189 variant showed higher fasting serum insulin level and higher HOMA-IR level than those without 16189 variant; stepwise multiple regression analysis showed the 16189 variant was an independent factor contributing to HOMA-IR (R(2)=0.043, P=0.037). Secondary structure prediction revealed that there were differences in 3394 T-->C vs wild-type ND1 protein and in 14693 A-->G vs wild-type tRNA(Glu) protein. CONCLUSION: The mutations of 3394 (T-->C) and 14693 (A-->G) may contribute to the genetic predisposition to type 2 diabetes; 16189 (T-->C) variant is associated with insulin resistance and risk factor of diabetes.