SNP-STR遗传标记复合扩增体系的构建及法医学应用

目的筛选并构建与目前STR数据库兼容的SNP-STR遗传标记复合扩增体系,调查其在四川汉族群体中的遗传多态性,并探讨其在混合DNA样本分析中的应用价值。方法以现有商业试剂盒中使用的STR遗传标记为基础,筛选与STR遗传标记相邻的SNP位点并组成SNP-STR遗传标记。运用SNP等位基因设计特异性引物,构建基于等位基因特异性扩增的SNP-STR遗传标记复合扩增体系。调查该体系在四川汉族群体的遗传多态性,并评价不同位点数目的体系对两个体混合DNA样本的检测效能。结果筛选并构建了由13个SNP-STR遗传标记构成的等位基因特异性复合扩增体系。在四川汉族群体中,各位点杂合度为0.76~0.88,累积个体识别率达0.999 999 999 999 999 968。在对两个体混合DNA的分析中:单位点扩增时,混合样本的混合比例达到1 000∶1时依然可以检测到少量成分所特有的分型;多位点复合扩增时,混合比例最大可达500∶1;随着体系中位点数量的增加,对混合DNA中少量成分的检测效能降低。结论SNP-STR遗传标记较STR具有更高的多态性,其构成的复合扩增体系对混合样本的分析效能优于传统的STR复合扩增体系。

Construction of SNP-STR Multiplex Amplification System with Genetic Markers and Its Forensic Application

Objective To select and develop a SNP-STR multiplex amplification system with genetic markers compatible with current STR databases.To understand its genetic polymorphisms in Sichuan Han population and its application value in DNA mixture analysis.Methods Based on the STR genetic markers in commercial kits,SNPs adjacent to these STR markers were selected to be SNP-STR genetic markers.A SNP-STR multiplex amplification system with genetic markers based on allele-specific amplification was constructed using allele-specific amplification primers.The genetic polymorphism of the system in the Sichuan Han population was investigated and the efficiency of systems with different snpuemcibfeicrs mofu ltliopclie xt oa mdeptleifcitc atthioen t wsyos tienmdi vciodnusatli tuDteNdA ofm i1 xt3 u reS NsPa-m SplTeRs wgeanse teicva lmuaatrekde.r sR ewsausl tss elAenct eadll ealen-d constructed.In Sichuan Han population,the heterozygosity of each locus ranged from 0.76 to 0.88,and the combined discrimination power reached 0.999999999999999968.In the analysis of the two individual DNA mixture samples:for single-locus amplification,the genotype of the minor components can still be detected when the mixture ratio reaches 1000∶1;for multiple loci multiplex amplification,the maximum mixture ratio can reach 500∶1.As the number of loci in the system increased,the detection efficiency of the minor components in the DNA mixture decreased.Conclusion SNP-STR genetic markers have a higher polymorphism than STR.The multiplex amplification system made of SNPSTR genetic markers has a better analysis efficiency for mixed samples than traditional STR multiplex amplification system.