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The use of noninvasive human substrates to interrogate pathophysiological conditions has become essential in the post- Human Genome Project era. Due to its high turnover rate, and its long term capability to incorporate exogenous and endogenous substances from the circulation, hair testing is emerging as a key player in monitoring long term drug compliance, chronic alcohol abuse, forensic toxicology, and biomarker discovery, among other things. Novel high-throughput 'omics based approaches like proteomics have been underutilized globally in comprehending human hair morphology and its evolving use as a diagnostic testing substrate in the era of precision medicine. There is paucity of scientific evidence that evaluates the difference in drug incorporation into hair based on lipid content, and very few studies have addressed hair growth rates, hair forms, and the biological consequences of hair grooming or bleaching. It is apparent that protein-based identification using the human hair proteome would play a major role in understanding these parameters akin to DNA single nucleotide polymorphism profiling, up to single amino acid polymorphism resolution. Hence, this work seeks to identify and discuss the progress made thus far in the field of molecular hair testing using proteomic approaches, and identify ways in which proteomics would improve the field of hair research, considering that the human hair is mostly composed of proteins. Gaps in hair proteomics research are identified and the potential of hair proteomics in establishing a historic medical repository of normal and disease-specific proteome is also discussed.

Background: ‘Haircut-associated bleeding' is a newly recognized entity that affects at least a quarter of African men who wear shiny clean-shave (‘chiskop') haircuts. Aim: This pilot study aimed to elucidate whether invisible haircut-associated bleeding was detectable using blood specific RNA markers (16 participants, 5 with unknown HIV status) and whether surface virus could be detected using PCR from scalp swabs (of 11 known HIV-positive participants). Methods: Haircuts were performed professionally and scalps examined by a dermatologist to exclude injury. Serum samples for viral loads were also collected at the same time. Results: In all, 6/16 (37%) samples tested positive (>100 relative fluorescent units) for hemoglobin beta and albumin, confirming evidence of blood; of these, only 1/11 was HIV-positive but had an undetectable serum viral load. No surface HIV was detected from any scalp samples. Conclusions: This study confirms the entity of haircut-associated bleeding but goes further to show for the first time that invisible bleeding from clean-shave haircuts is also common. Both a high serum viral load and evidence of bleeding should ideally be present prior to surface HIV detection. Future investigations for potential HIV (and hepatitis B) transmission through clean-shave haircuts are warranted but should not delay public education for disease prevention.