摘要
目的通过对213例耳聋患者和120例正常对照进行线粒体12S rRNA突变筛查后,发现2个携带线粒体A1555G突变的聋病家系,并对其进行临床和分子遗传学评估,探讨耳聋的分子机制。方法使用PCR对2个耳聋家系的母系成员进行线粒体基因组的扩增并进行Sanger测序,测序结果与线粒体标准序列比对,筛选突变位点。同时对突变进行保守性分析、tRNA二级结构分析,评估突变的致病性。结果2个耳聋家系有较高的外显率,分别为66.6%和62.5%,明显高于其他携带A1555G突变的耳聋家系。线粒体基因组测序分析后发现存在12S rRNA A1555G,tRNAThr A15924G和G15927A突变,分别属于东亚线粒体单体型B4cl和B5b。A15924G和G15927A突变位于tRNAThr反密码子环,在进化上高度保守,突变可能影响tRNAThr的二级结构和功能,从而导致线粒体功能缺陷。未发现其他有功能学意义的突变位点。结论线粒体tRNAThrA15924G和G15927A可能是耳聋有关的继发性突变位点,通过影响tRNAThr的代谢并加重A1555G突变引起的线粒体功能损伤,进而增加耳聋的外显率和表现度。
Objective To investigate the molecular mechanism of deafness by evaluating the clinical and molecular genetics of two deaf genealogies with mitochondrial A1555G mutation after screening 213 deaf patients and 120 normal controls for mitochondrial 12S rRNA mutation.Methods PCR was used to amplify complete mitochondrial genomes of matrilineal relatives of two deaf genealogies and Sanger sequencing was used.The sequencing results were compared with the mitochondrial standard sequence,and the mutation sites were screened.Furthermore,the pathogenicity of these identified mutations was assessed by evolutionary conservation analysis,tRNA secondary structure analysis.Results We found that these pedigrees had relatively high penetrances(66.6%and 62.5%)than other genealogies with mitochondrial A1555G mutation.Sequence analysis of the mitochondrial genomes from the matrilineal relatives suggested the existence of A1555G,as well as tRNAThr A15924G and G15927A mutations,which belonged to East Asian mitochondrial haplogroups B4cl and B5bl,respectively.Further analysis indicated that the A15924G and G15927A mutations were localized at anticodon loop of tRNAThr,which were very highly conserved from different species.The A15924G and G15927A mutations may affect the structure and function of tRNAThr,as a result,these mutations may cause mitochondrial dysfunction.In addition,we did not find any other functional variants in mitochondrial genomes.Conclusion Mitochondrial tRNAThr A15924G and G15927A may be the secondary mutation sites associated with deafness,which may enhance the mitochondrial dysfunction caused by the A1555G mutation via the regulation of tRNAThr metabolism,and increase the penetrance and expressivity of deafness.
出处
《浙江临床医学》
2022年第3期340-343,共4页
Zhejiang Clinical Medical Journal
基金
浙江省医药卫生科技计划项目(2021RC022)。
