RT-ARMS-qPCR定量测定线粒体耳聋患者mtDNA A1555G位点突变

目的 探讨RT-ARMS-qPCR(real time amplification refractory mutation system quantitativePCR)系统定量测定线粒体DNA(mitochondrial DNA,mtDNA)A1555G位点突变在线粒体耳聋发病机制研究中的价值.方法 以PeR扩增含mtDNA 1555位点的片段,并将其克隆到pGEM-T Easy载体上,构建质粒标准品;在引物3'端插入错配碱基AC建立RT-ARMS-qPCR系统,对含突变型和野生型mtDNA 1555位点片段的12例线粒体耳聋患者进行定量检测.结果 RT-ARMS-qPCR系统在检测1个含野生型mtDNA 1555的重组质粒DNA模板时,其批内变异系数(CV)为1.34%,批间CV为1.96%,线性范围为102-108拷贝/ul;突变型或野生型引物只特异扩增相对应的序列,特异性好;突变型/野生型mtDNA拷贝数及突变型所占的百分比与耳聋的严重程度相关(r=0.771,P=0.003),突变型mtDNA所占的比例越高,耳聋程度越严重.结论 RT-ARMS-qPCR系统适合于定量检测mtDNAA1555G点突变的线粒体DNA片段,结果特异、稳定、准确.线粒体耳聋的严重程度与含突变型和野生型mtDNA 1555位点的拷贝数比例有关.

Quantitation of mitochondrial DNA A1555G mutation by real time amplification refractory mutation system quantitative PCR

Objective To develop a real time amplification refractory system(RT-ARMS-qPCR) quantitative PCR method with SYBR Green I to assess the mtDNA A1555G mutation. Methods A specific fragment flanking mtDNA 1555 site was amplified with PCR and ligated into a pGEM Easy T vector. Serial dilutions of the plasmid DNA were quantified the actual copy numbers were assessed using RF-ARMS-qPCR with SYBR Green I. RF-ARMS-qPCR was established with mismatched base pairs at 3' in the primer todetect the copy number of mtDNA containing wild or mutant mtDNA. The specificity of amplified products was checked by melting curve analysis. Results The intra- and interassay variation was 1.34% and 1.96%, respectively when the assay was used to detect 1 copy/ul recombinant template of plasmid. Thequantitative standard curve showed that the assay had good linear correlation from 102 copies/ul to108 copies/ul. This assay could be served for the quantification of other samples. There was significantcorrelation between frequency of mutant mtDNA and phenotype (r=0.771, P = 0.003) in hearing lossgroup. Conclusions The established assay can be used to detect quantitatively mtDNA A1555G mutation byRF-ARMS-qPCR. This assay is specific, stable and accurate. There is significant correlation betweenquantification of mtDNA AI555G and the severity of hearing loss.