氨基糖甙类抗生素致聋家系线粒体DNA12S和16S rRNA基因突变分析

摘要

目的研究线粒体rRNA基因突变与氨基糖甙类抗生素致聋遗传易感性的关系,为建立相应的基因诊断方法提供依据.方法收集了五个有明确氨基糖甙类抗生素应用史的耳聋家系共27名成员的外周静脉血标本,从白细胞中提取DNA,PCR扩增线粒体DNA片段,Alw26I限制性内切酶分析和DNA序列分析检测A1555G点突变,并对其中一个家系进行了线粒体DNA12S和16S rRNA基因的全序列分析.结果家系A、C、D和E的21份样品均为A1555G点突变阳性,家系B的6份样品为A1555G点突变阴性.家系B线粒体DNA12S和16SrRNA 基因全序列分析显示该家系存在16S rRNA基因第2227位"AA"插入突变.结论本研究发现了一个A1555G点突变阴性的氨基糖甙类抗生素致聋家系,说明线粒体SNA A1555G 点突变不是氨基糖甙类抗生素遗传易感性唯一的分子基础,对氨基糖甙类抗生素致聋遗传易感性的预测仅检测A1555G点突变是不够的,应与mtDNA其它相关突变位点的检测结合起来.%Objective It has been reported that familial aminoglycoside-induced deafness is mitochondrial inheritance and is associated with a homoplasmic A to G mutation at nucleotide 1555 in the mitochondrial 12S ribosomal RNA gene. However, it is not clear whether the A1555G mutation is the sole pathogenic mitochondrial DNA mutation associated with aminoglycoside-induced deafness. The aim of the present study is to search and locate other possible mutations which may also be involved in this disease. Methods Twenty-seven blood samples were obtained from five families with aminoglycoside-induced deafness for screening the A1555G mutation. Results Alw26 I digestion of PCR products showed that twenty-one samples from four families carried homoplasmic A1555G mutation, but six samples from one family did not have the 1555G mutation.Mitochondrial 12S and 16S ribosomal RNA genes were amplified by PCR from two patients of the family without 1555G mutation and were sequenced thoroughly to find novel DNA mutations associated with aminoglycoside-induced deafness. Both patients shared two bases of AA insertion at nucleotide 2227 in 16Sribosomal RNA gene. Conclusion Our finding implies that the A1555G mutation is not the sole pathogenic mutation in aminoglycoside-induced deafness. Further studies will be done to determine whether 2227AAinsertion is a pathogenic mutation or a benign sequence variation and to investigate the functional effect of this putative mutation.