Forensic Body Fluid RNA Typing: Evaluating the Roles of CE and dPCR Technologies

The identification of body fluids in forensic science has increasingly relied on RNA-based approaches due to their tissue specificity and ability to provide probative information beyond DNA profiling. Among the analytical platforms used for RNA detection, capillary electrophoresis (CE) has traditionally served as the standard method in forensic laboratories, offering established workflows and effective multiplexing capabilities. However, recent studies in digital PCR (dPCR) have introduced a highly sensitive alternative that enables absolute quantification of target transcripts without reliance on standard curves, particularly beneficial for low-template and degraded forensic samples. This short review provides a focused comparative evaluation of CE- and dPCR-based workflows for RNA-based body fluid identification, emphasizing analytical performance and forensic applicability. Key parameters, including sensitivity, specificity, multiplexing capacity, tolerance to degraded RNA, and interpretation methods, are critically assessed. CE remains advantageous for multiplex assay design and routine forensic implementation due to its established infrastructure and throughput. In contrast, dPCR demonstrates superior sensitivity and quantitative precision, particularly in challenging forensic samples, but is currently limited by reduced multiplexing capacity and higher costs. The review highlights the methodological strengths and limitations of both platforms and examines their suitability for forensic casework. Overall, CE and dPCR are not positioned as competing replacements at the moment but rather as complementary technologies, with their combined or context-dependent use offering improved robustness in RNA-based forensic body fluid identification. Further validation and standardization studies are required to support broader implementation of dPCR in routine forensic workflows.