Department of Forensic Science, Virginia Commonwealth University, Richmond, Virginia, USA.
Integrative Life Sciences, Virginia Commonwealth University, Richmond, Virginia, USA.
J Forensic Sci. 2022 Jul;67(4):1668-1678. doi: 10.1111/1556-4029.15027. Epub 2022 Mar 14.
The prevalence of sexual assault cases and increasingly sensitive DNA analysis methods have resulted in sexual assault kit backlogs in the United States. Although traditional DNA extraction and purification utilizing detergents, proteinase K, and DTT have been the primary technique for lysing sperm cell fractions from these samples, it is labor-intensive and inefficient regarding time and sperm DNA recovery - hindering the ability of forensic analysts to keep pace with evidence submissions. Thus, this study examined seven alternative sperm cell lysis techniques to develop a method that could efficiently lyse sperm and consistently generate high-quality profiles while also reducing time, labor, and cost requirements. Microscopic examination of lysates indicated only Casework Direct and alkaline techniques could lyse all spermatozoa within samples, while quantification results demonstrated all methods performed comparably to the control method of forensicGEM™ Sperm (p > 0.06). Amplification with 0.25 ng DNA revealed that unpurified lysates from Casework Direct, alkaline, and NP-40 techniques produced DNA profiles with acceptable mean STR peak heights and interlocus balance, both of which were similar to or better than the control. Overall, this study demonstrated the ability of Casework Direct, alkaline, and NP-40 methods to efficiently lyse spermatozoa and provide high-quality STR profiles despite the absence of a purification step. Ultimately, based on the data reported herein, alkaline lysis is the recommended alternative sperm lysis approach given its ability to generate high-quality profiles, save time, and decrease the cost per reaction when compared to traditional sperm cell lysis methods.
性侵犯案件的普遍存在和日益敏感的 DNA 分析方法导致美国性侵犯工具包积压。尽管传统的 DNA 提取和纯化利用洗涤剂、蛋白酶 K 和 DTT 一直是从这些样本中裂解精子细胞部分的主要技术，但它在时间和精子 DNA 回收方面效率低下，阻碍了法医分析人员跟上证据提交的步伐。因此，本研究考察了七种替代的精子细胞裂解技术，以开发一种能够有效地裂解精子并始终产生高质量图谱的方法，同时减少时间、劳动力和成本要求。裂解物的显微镜检查表明，只有 Casework Direct 和碱性技术可以裂解样本中的所有精子，而定量结果表明，所有方法与法医 GEM™Sperm 的对照方法性能相当（p>0.06）。用 0.25ng DNA 进行扩增表明，来自 Casework Direct、碱性和 NP-40 技术的未纯化裂解物产生的 DNA 图谱具有可接受的平均 STR 峰高和等位基因间平衡，这两者均与对照相似或更好。总的来说，这项研究表明 Casework Direct、碱性和 NP-40 方法能够有效地裂解精子并提供高质量的 STR 图谱，尽管缺乏纯化步骤。最终，根据本文报告的数据，碱性裂解是推荐的替代精子裂解方法，因为与传统的精子细胞裂解方法相比，它能够生成高质量的图谱，节省时间并降低每个反应的成本。
