Ding Yu, Yu Jinfang, Gao Beibei, Huang Jinyu
Central Laboratory, Hangzhou First People's Hospital, Hangzhou, Zhejiang 310006, China.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi. 2023 Jul 10;40(7):807-814. doi: 10.3760/cma.j.cn511374-20220729-00504.
To explore the correlation of mitochondrial DNA (mtDNA) variants and coronary heart disease (CHD) in a Chinese pedigree and the possible molecular mechanisms.
A Chinese pedigree featuring matrilineal inheritance of CHD who visited Hangzhou First People's Hospital in May 2022 was selected as the study subject. Clinical data of the proband and her affected relatives was collected. By sequencing the mtDNA of the proband and her pedigree members, candidate variants were identified through comparison with wild type mitochondrial genes. Conservative analysis among various species was conducted, and bioinformatics software was used to predict the impact of variants on the secondary structure of tRNA. Real-time PCR was carried out to determine the copy number of mtDNA, and a transmitochondrial cell line was established for analyzing the mitochondrial functions, including membrane potential and ATP level.
This pedigree had contained thirty-two members from four generations. Among ten maternal members, four had CHD, which yielded a penetrance rate of 40%. Sequence analysis of proband and her matrilineal relatives revealed the presence of a novel m.4420A>T variant and a m.10463T>C variant, both of which were highly conserved among various species. Structurally, the m.4420A>T variant had occurred at position 22 in the D-arm of tRNAMet, which disrupted the 13T-22A base-pairing, while the m.10463T>C variant was located at position 67 in the acceptor arm of tRNAArg, a position critical for steady-state level of the tRNA. Functional analysis revealed that patients with the m.4420A>T and m.10463T>C variants exhibited much fewer copy number of mtDNA and lower mitochondrial membrane potential (MMP) and ATP contents (P < 0.05), which were decreased by approximately 50.47%, 39.6% and 47.4%, respectively.
Mitochondrial tRNAMet 4420A>T and tRNAArg 10463T>C variants may underlay the maternally transmitted CHD in this pedigree, which had shown variation in mtDNA homogeneity, age of onset, clinical phenotype and other differences, suggesting that nuclear genes, environmental factors and mitochondrial genetic background have certain influence on the pathogenesis of CHD.
探讨中国一个家系中线粒体DNA（mtDNA）变异与冠心病（CHD）的相关性及可能的分子机制。
选取2022年5月就诊于杭州市第一人民医院的一个具有冠心病母系遗传特征的中国家系作为研究对象。收集先证者及其患病亲属的临床资料。通过对先证者及其家系成员的mtDNA进行测序，与野生型线粒体基因比较确定候选变异。进行不同物种间的保守性分析，并使用生物信息学软件预测变异对tRNA二级结构的影响。采用实时荧光定量PCR测定mtDNA拷贝数，并建立线粒体细胞系分析线粒体功能，包括膜电位和ATP水平。
该家系包含来自四代的32名成员。在10名母系成员中，4人患有冠心病，外显率为40%。对先证者及其母系亲属的序列分析显示存在一个新的m.4420A>T变异和一个m.10463T>C变异，这两个变异在不同物种间高度保守。在结构上，m.4420A>T变异发生在tRNAMet的D环第22位，破坏了13T-22A碱基对，而m.10463T>C变异位于tRNAArg接受臂的第67位，该位置对tRNA的稳态水平至关重要。功能分析显示，携带m.4420A>T和m.10463T>C变异的患者mtDNA拷贝数、线粒体膜电位（MMP）和ATP含量明显减少（P<0.05），分别降低了约50.47%、39.6%和47.4%。
线粒体tRNAMet 4420A>T和tRNAArg 10463T>C变异可能是该家系母系遗传冠心病的基础，该家系在mtDNA同质性、发病年龄、临床表型等方面存在差异，提示核基因、环境因素和线粒体遗传背景对冠心病发病机制有一定影响。
