Two-person DNA mixture interpretation based on a novel set of SNP-STR markers
Two-person DNA mixture interpretation based on a novel set of SNP-STR markers
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基于一组新型 SNP-STR 标记的两人 DNA 混合物解释
DOI：
10.1016/j.fsigen.2018.07.021
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发表时间：
2018-11-01
影响因子：
3.1
通讯作者：
Zhang, Lin
中科院分区：
文献类型：
--
作者：
Tan, Yu;Bai, Peng;Zhang, Lin
通过聚合酶链反应（PCR）和毛细管电泳（CE）分析的常染色体短串联重复序列（STR）标记是法医DNA分析的金标准。随着检测设备灵敏度的提高，从微量DNA中可以获得更多的混合DNA图谱，而这些微量DNA在以往通常表现为单一来源。更具体地说，在法医案件工作中经常会遇到包含受害者和犯罪者DNA的双源DNA混合物，其中受害者的DNA是混合物的主要成分。不幸的是，比例大于20∶1的不平衡双人DNA混合物（在此我们将这种混合物称为极度不平衡DNA混合物）对次要成分提供的信息有限。尽管概率软件的开发使混合DNA结果的解释变得更容易，但考虑到次要成分，高混合比例会导致似然比（LR）无信息价值。因此，一种能够在常规CE平台上进行，同时提高在极度不平衡DNA混合物中检测微量DNA能力的技术，在法医案件工作中可能非常有用。我们之前的研究报告称，单核苷酸多态性 - 短串联重复序列（SNP - STR）结合基于扩增受阻突变体系（ARMS）的PCR技术，可用于解析极度不平衡的双人DNA混合物。为了进一步探索SNP - STR标记帮助分析此类DNA混合物的能力，我们开发了11种新的SNP - STR标记。然后使用基于ARMS的PCR设计等位基因特异性引物，其中每个引物针对位于串联重复序列侧翼区域的一个SNP等位基因。这种方法使引物能够特异性和选择性地扩增微量DNA，而不受主要成分DNA的干扰，因为所选的SNP等位基因与主要贡献者不共享。对中国西南汉族人群中所选的11个SNP - STR的调查显示出高度的多态性。对双人DNA混合物的检测表明，即使主要DNA的量高出100倍，所有等位基因特异性引物都能靶向微量DNA。因此，这组新的SNP - STR标记为分析极度不平衡的双人DNA混合物提供了一种替代方法。
Autosomal short tandem repeats (STR) markers analysed by PCR and capillary electrophoresis (CE) represent the gold-standard for forensic DNA analysis. With the improved sensitivity of detection equipment, a larger number of mixed DNA profiles can be obtained from trace amounts of DNA that conventionally used to appear as a single source. More specifically, two-source DNA mixtures, comprising the victim's and the perpetrator's DNAs, are often encountered in forensic casework, where the victim's DNA represents a major component of the mixture. Unfortunately, unbalanced two-person DNA mixtures with a ratio larger than 20:1 (here we have named this kind of mixture extremely unbalanced DNA mixture) provide limited information on the minor component. Although the development of probabilistic software has made interpretation of results from mixed DNA easier, high mixture ratios lead to an uninformative likelihood ratio (LR), considering the minor component. Therefore, a technique that can be performed on the conventional CE platform, while enhancing the ability to detect minor DNA in extremely unbalanced DNA mixtures, may be very useful in forensic casework. Our previous research has reported that SNP-STRs, in conjunction with a PCR technique based on amplification refractory mutation system (ARMS), can be used to resolve extremely unbalanced two-person DNA mixtures. To further explore the capacity of SNP-STR markers to help analyse such DNA mixtures, we developed 11 novel SNP-STR markers. The ARMS-based PCR was then used to design allele-specific primers, where each primer targeted one SNP allele located in the flanking region of the tandem repeats. This method allowed primers to specifically and selectively amplify minor DNA without interference from DNA of the major component because the selected SNP allele was not shared with the major contributor. A survey of the selected 11 SNP-STRs in a southwest Chinese Han population showed high levels of polymorphism. Assays on two-person DNA mixtures showed that all the allele-specific primers could target minor DNA even when the amount of major DNA was a 100-fold higher. Therefore, this novel set of SNP-STR markers provides an alternative method for the analysis of extremely unbalanced two-person DNA mixtures.