Klein Sonja B, Buoncristiani Martin R
State of California, Department of Justice, Jan Bashinski DNA Laboratory, 1001 W. Cutting Blvd., Richmond, CA 94804, USA.
State of California, Department of Justice, Jan Bashinski DNA Laboratory, 1001 W. Cutting Blvd., Richmond, CA 94804, USA.
Forensic Sci Int Genet. 2017 Jul;29:109-117. doi: 10.1016/j.fsigen.2017.03.021. Epub 2017 Mar 31.
Analysis of sexual assault evidence, often a mixture of spermatozoa and victim epithelial cells, represents a significant portion of a forensic DNA laboratory's case load. Successful genotyping of sperm DNA from these mixed cell samples, particularly with low amounts of sperm, depends on maximizing sperm DNA recovery and minimizing non-sperm DNA carryover. For evaluating the efficacy of the differential extraction, we present a method which uses a Separation Potential Ratio (SPRED) to consider both sperm DNA recovery and non-sperm DNA removal as variables for determining separation efficiency. In addition, we describe how the ratio of male-to-female DNA in the sperm fraction may be estimated by using the SPRED of the differential extraction method in conjunction with the estimated ratio of male-to-female DNA initially present on the mixed swab. This approach may be useful for evaluating or modifying differential extraction methods, as we demonstrate by comparing experimental results obtained from the traditional differential extraction and the Erase Sperm Isolation Kit (PTC) procedures.
性侵犯证据分析，通常是精子和受害者上皮细胞的混合物，占法医DNA实验室案件量的很大一部分。从这些混合细胞样本中成功进行精子DNA基因分型，尤其是精子数量较少时，取决于最大限度地回收精子DNA并最小化非精子DNA的残留。为了评估差异提取的效果，我们提出了一种方法，该方法使用分离潜力比（SPRED），将精子DNA回收和非精子DNA去除都视为确定分离效率的变量。此外，我们描述了如何通过将差异提取方法的SPRED与混合拭子上最初存在的男女DNA估计比例相结合，来估计精子部分中男女DNA的比例。正如我们通过比较传统差异提取和擦除精子分离试剂盒（PTC）程序获得的实验结果所证明的那样，这种方法可能有助于评估或修改差异提取方法。
