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目的 探索中国人 2型糖尿病与线粒体变异的关系。方法 针对已经报道的线粒体基因的高发突变区(mt315 3～ 35 5 1)近 40 0bp的片段在中国人正常人群、2型糖尿病群体及 12个母系遗传的 2型糖尿病家系中进行聚合酶链反应 单链构象多态性 (polymerasechainreaction singlestrandconformationpolymorphism ,PCR SSCP)研究 ,发现异常构象再进行DNA序列测定。结果 正常人群中该区域DNA经PCR SSCP电泳后未见异常条带出现 ,2型糖尿病人群中该区域DNA经PCR SSCP电泳后第 81号患者出现异常条带 ,直接测序发现的点突变 3336T→C(ATT→ATC ,均编码Ⅰle) ,并没有引起ND1基因编码区氨基酸序列的改变 ;2 5 0 0 1家系是本研究中唯一通过PCR SSCP检测发现有电泳带型改变的家系 ,经过直接测序发现该突变发生在mtDNA32 85bp(T→C/T) ,为一杂合突变 ,且点突变位于tRNALeu(UUR) 基因的编码范围内。结论 线粒体DNA315 3～ 35 5 1bp间的突变不是本研究中国人群 2型糖尿病的主要发病原因 ;家系 2 5 0 0 1中发现的点突变 32 85T→C/T位于tRNALeu(UUR) 基因高度保守的区域内 ,有可能通过影响tRNALeu(UUR) 的三级结构而致功能缺陷 ,不能执行正常的翻译功能 ,使线粒体内编码与呼吸链有关的多肽发生功能缺陷而使线粒体内氧化磷酸化
Objective To explore the relationship between type 2 diabetes and mitochondrial variation in Chinese. Methods A polymerase chain reaction (PCR) was performed in nearly normal human population, type 2 diabetes mellitus and 12 matrine-typed type 2 diabetes mellitus families in the highly reported mutation region of mitochondrial DNA (mt315 3 ~35 5 1) Single strand conformation polymorphism (PCR SSCP) study found that abnormal conformation DNA sequence determination. Results No abnormal bands appeared in normal population after PCR SSCP electrophoresis. Abnormal bands appeared in patients with type-2 diabetes in No. 81 after PCR SSCP electrophoresis. The point mutation 3336T → C (ATT → ATC, both coded Ile) did not change the amino acid sequence of the coding region of ND1 gene. The 2505 pedigree was the only pedigree found by PCR SSCP in this study to be detected by direct sequencing. The mutation occurred in mtDNA32 85bp (T → C / T), a heterozygous mutation, and point mutation in the coding region of tRNALeu (UUR) gene. Conclusions Mutations of mitochondrial DNA between 315 and 35 5 1bp are not the main cause of type 2 diabetes in Chinese population. The point mutation 32 85T → C / T found in pedigree 25001 is highly conserved in the tRNALeu (UUR) gene Region, it is possible to cause functional defects by affecting the tertiary structure of tRNALeu (UUR), failing to perform normal translation functions, and causing mitochondrial oxidative phosphorylation