Potential of Proteomics in Forensic Phenotyping: A Focus on Biological Sex Estimation

Forensic DNA analysis is well established for phenotyping,
providing
valuable investigative leads. Proteomics, the large-scale study of
proteins, is emerging as a complementary tool to DNA analysis, particularly
for enhancing the evidential value of traces. This study explores
the potential of proteomics to extract phenotypic traits from whole
blood, using the estimation of biological sex as a starting point.
Using LC–MS/MS, proteomes from 100 whole blood samples of known
sex were analyzed to develop a biological sex classifier. Cross-validation
of the model highlighted the model’s ability to achieve accurate
classification, identifying key peptides, such as those from pregnancy
zone protein and ceruloplasmin, as critical markers. To test real-world
applicability, mock case samples were generated, bringing attention
to the need for model robustness. Overall, our results suggest that
using proteomics to infer phenotypic traits from whole blood samples
in the context of forensics, while feasible, is hindered by hard-to-overcome
technical challenges. We therefore recommend that future forensic
proteomics research be directed toward areas where it can be most
informative, such as source attribution and estimating the timeline
of events, rather than focusing on extracting phenotypic traits for
donor profiling.