Enhanced DNA mixture deconvolution of sexual offense samples using the DEPArray™ system

The interpretation of DNA mixtures remains a significant challenge in the analysis of forensic evidence. The ability to selectively identify, collect, and analyze single cells or groups of cells has wide implications in the analysis of forensic samples and the subsequent deconvolution of DNA mixtures, particularly in the processing and interpretation of sexual offense evidence where the deconvolution of heterogeneous sources is essential. Single cell separation technology can be used to address this mixture separation challenge, specifically using the DEPArray™ system from Menarini Silicon Biosystems. We propose that the DEPArray™ will enable enhancements to the standard workflow for forensic biology/DNA analytical laboratories. We have demonstrated that the DEPArray™ workflow will lead to fewer mixture samples, enable purification of sperm and epithelial cell fractions without the need for differential extraction, improve the amplification success rate of samples and improve the interpretation of low template DNA samples. Sperm profiles were identified in 27 of 32 DEPArray™ processed samples, with 26 of 27 (96.2%) yielding single source profiles. In contrast, single source profiles were obtained from 9 of 28 (32.1%) differentially extracted samples. The use of the DEPArray™ also eliminates the need for additional confirmatory tests for the presence of human sperm and permits direct identification of the type and number of cells being analyzed eliminating the need for qPCR-based DNA quantification.