全基因组扩增在微量检材DNA分型中的应用

The application of whole genome amplification in DNA typing of trace samples

目的探索全基因组扩增技术对微量检材DNA分型的有效性。方法通过显微操作制备含1~20个细胞的模拟微量检材样本,在常规PCR-STR分型前加入全基因组扩增步骤,从等位基因不平衡、等位基因丢失、基因座丢失、伪等位基因(包含stutter峰)等方面探究PEP和MDA两种全基因组扩增方法对微量检材DNA分型的有效性。结果 MDA扩增效率高于PEP,但等位基因丢失和伪等位基因严重;PEP方法的正确分型率高于MDA,但小片段DNA优势扩增现象较严重。结论 MDA方法并不适合目前以STR分型为主导的法庭科学,当微量检材样本的绝对量相当少时,可以考虑使用PEP方法来扩大样本量,以满足重复检验的要求,但可能面临大片段DNA扩增失败的风险。

Objective To explore the effectiveness of whole genome amplification technology in DNA typingof trace samples. Methods Simulated trace samples which contain 1-20 cells were prepared by micromanipulation.Whole genome amplification was added before conventional PCR-STR typing step, to compare the effectiveness of PEPand MDA in DNA typing of trace samples from four aspects i.e. allele imbalance, allele drop-out, locus drop-out andpseudo allele （which contains the stutter peak）. Results Amplification efficiency of MDA was higher than PEP method,but allele drop-out and pseudo allele were more frequently detected. Correct DNA typing rate of PEP is higher thanMDA method, however, advantaged amplification of small fragments DNA is more obvious. Conclusion MDA methodis not suitable for the current STR typing. When the absolute amount of trace samples is quite small, we couldconsiderusing the PEP method to enhancethe sample quantity to meet the requirement of repeat testing. At the same time itcould encounterthe failure of the large DNA fragments.