Wu Jie, Li Jing-Long, Wang Meng-Lei, Li Jian-Ping, Zhao Zhi-Chao, Wang Qi, Yang Shu-Dong, Xiong Xin, Yang Jing-Long, Deng Ya-Jun
Institute of Beijing DNA Evidence, Beijing, 101318, People's Republic of China.
Int J Legal Med. 2019 May;133(3):689-697. doi: 10.1007/s00414-018-01987-x. Epub 2019 Jan 2.
Capillary electrophoresis (CE) is widely used in forensic genetics to study short tandem repeats (STRs). Recently, next-generation sequencing (NGS) platforms have facilitated the development of new strategies for forensic DNA typing. Several studies have shown that NGS successfully analyzes challenging samples. However, because NGS is complicated and time-consuming, it remains unclear whether NGS platforms offer significant advantages over CE for all forensic cases. Here, the MiSeq FGx system was used to test some cases that had previously been analyzed using CE. These cases included paternity test cases in which some samples exhibited locus inconsistencies; samples with off-ladder (OL) alleles; samples with triallelic patterns; and samples with amelogenin test abnormalities. The results generated by MiSeq FGx were compared to those previously generated by CE. The MiSeq FGx and CE results were consistent with the exception of three samples, where inconsistencies were observed at the Penta D locus. For all three incongruent samples, the MiSeq FGx results were correct. Sequence analysis indicated that, in two cases, mismatches were due to undetected alleles rather than mutations. In two additional cases, mutation sources were identified, and in a fifth case, mutation step size was reconsidered. MiSeq FGx was used to identify OL alleles and samples with amelogenin test abnormalities. For cases where verification was required via CE analysis, the simultaneous NGS amplification of several types of multiple genetic markers improved testing efficiency. In addition, we identified additional sequence variants at autosomal, Y chromosomal, and X chromosomal STR loci in the Han Chinese population from northern China. Our results will be useful for future forensic analyses of STR genotypes in Chinese populations. It is likely that NGS would be more widely used in forensic genetics if costs and procedure complexity were reduced.
毛细管电泳（CE）在法医遗传学中被广泛用于研究短串联重复序列（STR）。近年来，新一代测序（NGS）平台推动了法医DNA分型新策略的发展。多项研究表明，NGS成功分析了具有挑战性的样本。然而，由于NGS复杂且耗时，对于所有法医案件而言，NGS平台是否比CE具有显著优势仍不明确。在此，使用MiSeq FGx系统对一些先前已通过CE分析的案件进行检测。这些案件包括一些样本存在基因座不一致的亲子鉴定案件；具有非标准等位基因（OL）的样本；具有三等位基因模式的样本；以及牙釉蛋白检测异常的样本。将MiSeq FGx产生的结果与先前CE产生的结果进行比较。除了三个样本外，MiSeq FGx和CE的结果一致，在这三个样本中，五聚体D基因座出现了不一致。对于所有三个不一致的样本，MiSeq FGx的结果都是正确的。序列分析表明，在两个案例中，不匹配是由于未检测到的等位基因而非突变。在另外两个案例中，确定了突变来源，在第五个案例中，重新考虑了突变步长。MiSeq FGx用于鉴定OL等位基因和牙釉蛋白检测异常的样本。对于需要通过CE分析进行验证的案件，几种类型的多个遗传标记的同步NGS扩增提高了检测效率。此外，我们在中国北方汉族人群的常染色体、Y染色体和X染色体STR基因座上鉴定出了额外的序列变异。我们的结果将有助于未来对中国人群STR基因型进行法医分析。如果成本和程序复杂性降低，NGS很可能会在法医遗传学中得到更广泛的应用。
