Profiling Protein Expression Levels and Genetically Variant Peptides in Human Hair From Different Body Sites

Proteins of the human hair shaft contain a wealth of information about the coding regions of the person’s genome from whom the hair is derived. Commonly found at crime scenes, hair shafts may thus provide useful forensic evidence if the information they contain can be exploited. Present experiments show that hair shafts from four different anatomic sites are similarly useful in distinguishing individuals by protein profiling. However, the results demonstrated that protein profiles were dependent on anatomic site, indicating that a proper comparison requires matching the sites of origin. The differences in profile offer the prospect of determining the site of origin of hair by comparison with profiles of shafts from other anatomic sites. By contrast, the genetically variant peptides detected in the protein digests, that map to non-synonymous single nucleotide polymorphisms in subject DNA, were detectable regardless of the anatomic origin of the hair shafts. The resulting profiles of genetically variant peptides were more dependent on a subject’s genotype than on the anatomic origin of the hair shaft. Individual identification therefore can be based on peptide profiles regardless of body location. This study demonstrates the utility of proteomic analysis for increasing the forensic value of hair shaft evidence.