Sensitive DIP-STR markers for the analysis of unbalanced mixtures from "touch" DNA samples
Sensitive DIP-STR markers for the analysis of unbalanced mixtures from "touch" DNA samples
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DOI：
10.1016/j.fsigen.2017.02.004
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发表时间：
2017-05-01
影响因子：
3.1
通讯作者：
Hall, Diana
中科院分区：
文献类型：
--
作者：
Oldoni, Fabio;Castella, Vincent;Hall, Diana
收集用于法医DNA分析的案件样本可以产生基因组混合物，其中被指控罪犯的DNA被来自受害者的大量DNA掩盖。DIP-STR是专门开发的新型遗传标记，用于在存在超过第二个DNA数量(高达1000倍)的情况下对目标DNA进行靶标分析。该基因分型系统基于缺失/插入多态(DIP)和短串联重复序列(STR)形成的单倍型的等位基因特异性扩增，结合了针对个体DNA的能力和强大的识别能力。最后，DIP-STR是常染色体标记，因此它们可以应用于主要和次要DNA的任何组合。在本研究中，我们旨在评估DIP-STR在挑战具有代表性的犯罪相关底物模拟的“触摸”DNA样本时检测次要贡献者的能力，并将它们的性能与常用的男性特异性标记(Y-STR)进行比较。作为对两个接触同一物体的人的相对DNA贡献的综合研究的一部分，我们选择了71个不平衡的接触痕迹，其中14个包括男性次要DNA贡献者和女性主要DNA贡献者。使用一组六个DIP-STR，发现一到四个标记对于跨痕迹的微小DNA检测是有用的。与Y-STR(14个踪迹)相比，DIP-STR在检测底物材料上的微小DNA方面表现出类似的敏感性，并且等位基因丢失的发生率相似。相反，由于物体的两个使用者的性别组合，剩下的57个痕迹只能通过DIP-STR进行调查。在这些标记中，30个微小DNA贡献者可以被所有信息性标记检测到，而12个痕迹显示了等位基因丢失事件。最后，15个痕迹显示微小的DNA没有扩增。这15个样本的主要特点是处理时间短，DNA回收率低和/或单一的信息性DIP-STR。总之，DIP-STR是帮助解决不平衡的两个来源的DNA混合物的替代标记，也是由接触斑点产生的。这些标记，加上根据法医技术标准专门开发的一套新的10个DIP-STR，将为Y-STR标记提供一个宝贵的补充工具。(C)2017爱思唯尔B.V.保留所有权利。
Casework samples collected for forensic DNA analysis can produce genomic mixtures in which the DNA of the alleged offender is masked by high quantities of DNA coming from the victim. DIP-STRs are novel genetic markers specifically developed to enable the target analysis of a DNA of interest in the presence of exceeding quantities of a second DNA (up to 1000-fold). The genotyping system, which is based on allele-specific amplifications of haplotypes formed by a deletion/insertion polymorphism (DIP) and a short tandem repeat (STR), combines the capacity of targeting the DNA of an individual with a strong identification power. Finally, DIP-STRs are autosomal markers therefore they can be applied to any combination of major and minor DNA.In this study we aimed to assess the ability of DIP-STRs to detect the minor contributor on challenging "touch" DNA samples simulated with representative crime-associated substrates and to compare their performance to commonly used male-specific markers (Y-STRs). As part of a comprehensive study on the relative DNA contribution of two persons handling the same object, we selected 71 unbalanced contact traces of which 14 comprised a male minor DNA contributor mixed to a female major DNA contributor. Using a set of six DIP-STRs, one to four markers were found to be informative for the minor DNA detection across traces. When compared to Y-STRs (14 traces), the DIP-STRs showed similar sensitivity in detecting the minor DNA across substrate materials with a similar occurrence of allele drop-out. Conversely, because of the sex combination of the two users of the object, 57 remaining traces could only be investigated by DIP-STRs. Of these, 30 minor DNA contributors could be detected by all informative markers while 12 traces showed events of allele drop-out. Finally, 15 traces showed no amplification of the minor DNA. These last 15 samples were mostly characterized by a combination of short handling time of the object, low DNA recovery and/or one single informative DIP-STR.In conclusion, the DIP-STRs represent alternative markers to help solving unbalanced two-source DNA mixtures, and also those produced from contact stains. These markers, in addition to a novel set of 10 DIP-STRs specifically developed according to forensic technical standards, will offer a valuable tool complementary to Y-STR markers. (C) 2017 Elsevier B.V. All rights reserved.