Department of Forensic Biology, School of Forensic Medicine, Shanxi Medical University, Wenhua Street 55#, Jinzhong, 030619, Shanxi, People's Republic of China.
Int J Legal Med. 2021 Jan;135(1):13-21. doi: 10.1007/s00414-020-02288-y. Epub 2020 May 5.
The identification of a suspect in a degraded and unbalanced DNA mixture has been a challenge for the standard short tandem repeat polymorphisms (STR) typing. Several methods have been introduced to solve this problem, such as DIP-STR, DIP-SNP, and SNP-STR markers. In this study, we proposed DIP-microhaplotype (deletion/insertion linked a chain of SNPs) as a kind of new genetic marker to type the unbalanced and degraded DNA mixture. We established the detection method with ten DIP-microhaplotype markers including 26 SNPs using allele-specific multiplex PCR followed by SNaPshot assay. This novel compound marker allows us to detect the minor DNA with a sensitivity of 1:100 to 1:1000 in a DNA mixture of any gender. Most of the DIP-microhaplotype markers had a relatively high probability of informative alleles with an average informative value (I value) of 0.308. In all, we proposed DIP-microhaplotype as a novel type of DNA marker for the detection of minor contributor from unbalanced DNA mixtures. Due to their inherent shorter length, higher polymorphism, and sensitivity, DIP-microhaplotypes are promising markers for the examination of the degraded and unbalanced mixtures in forensic stains or clinical chimeras.
在降解和不平衡的 DNA 混合物中识别嫌疑人一直是标准短串联重复多态性 (STR) 分型的挑战。已经引入了几种方法来解决这个问题，例如 DIP-STR、DIP-SNP 和 SNP-STR 标记。在这项研究中，我们提出了 DIP-微单倍型（缺失/插入连锁 SNP 链）作为一种新的遗传标记来对不平衡和降解的 DNA 混合物进行分型。我们建立了使用等位基因特异性多重 PCR 结合 SNaPshot 分析检测包含 26 个 SNP 的 10 个 DIP-微单倍型标记的检测方法。这种新型复合标记允许我们在任何性别的 DNA 混合物中以 1:100 至 1:1000 的灵敏度检测到微量 DNA。大多数 DIP-微单倍型标记都具有相对较高的信息性等位基因概率，平均信息值 (I 值) 为 0.308。总之，我们提出 DIP-微单倍型作为一种新的 DNA 标记类型，用于检测不平衡 DNA 混合物中的微量供体。由于其固有的较短长度、较高的多态性和灵敏度，DIP-微单倍型是法医痕迹或临床嵌合体中降解和不平衡混合物检查的有前途的标记。
