# Proteomics in Forensic Analysis: Applications for Human Samples
## 3 Applications of Forensic Proteomics for Human Samples
### Bone Proteome
recently examined the relationship between PMI and the proteome of mouse bones under aquatic decomposition in four different types of aquatic environments, including tap water, saltwater, pond water, and chlorinated water [147]. They found that the effects of PMI on protein abundance were superior to those of the aquatic environment. Notably, muscle protein fructose-bisphosphate aldolase A (ALDOA) showed decreases in abundance with increasing PMI, whereas protein peptidyl-prolyl cis-trans isomerase (PPIA) and coagulation factor VII (F7A) could be potential biomarkers for distinguishing samples between terrestrial and aquatic environments. AHSG was used to potentially identify samples in pond water because it suffered significant deamidation in this environment compared to other aquatic environments. A recent study evaluated the proteome of whole skeletal elements using rats and determined protein biomarkers to estimate biological age [148]. They found five newly identified proteins that could be used for age estimation, including vimentin, osteepontin, matrilin-1, apolipoprotein A-I, and prothrombin. While the abundance of prothrombin increased with age, those of vimentin, osteepontin, matrilin-1, and apolipoprotein A-I showed an inverse trend (Figure 3d). Thus, these proteins, along with previously reported proteins (AHSG or fetuin-A, alpha-1 antitrypsin, chromogranin-A, albumin, KNG1, IGFBP5, SERPINF1, and biglyscan) have potential for development of an age estimation tool for skeletal samples in forensic contexts. Similar to human hair samples, human bone samples could be used to identify SAPs for human identification, although there have been few reports on this application. [PERSON] et al. recently performed proteomic analysis on human rib cortical bone samples and identified 15 proteins containing GVPs [43]. GVPs were correlated to unique DNA loci, and a total of 134 inferences were made. LR values were in the range of 1.4-825 with a median value of 16. GVPs obtained from the bone proteome can be effective in inferring SNP alleles, particularly when DNA is damaged. They can be used to match samples to ethnic groups and can be applied to human identification. Figure 3: Applications of bone proteomic analysis for estimation of biological age and post-mortem interval (PMI). (**a**) Boxplots of relative abundances of fetuin-A (AHSG), alpha-1-antitrypsin, and chromogranin-A in proteomic analysis of porcine tibia midshaft samples with varying biological age of pigs (P1077—12 days old, P1079—28-days old, P1076—43-days old, and P1081—10-months old). Figure was adapted with permission from [40]. Copyright (2017) American Chemical Society. (**b**) Relationship between age and the normalized emPAI value of alpha-2-HS-glycoprotein (AHSG), [PERSON]’s r = \(-\)0.9826, \(p\)-value = 1.295 \(\times\) 10\({}^{-5}\). Symbols are \(\square\) (infant), \(\circ\) (adult female), and \(\Delta\) (adult male). Figure was reprinted from [42], under the terms of the Creative Commons Attribution License (CC BY 4.0) [[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)) (accessed on 3 March 2021). (**c**) Box plot representing deamidation ratios calculated for the four tibas collected after one, two, four, and six months PMI. Each box represents five replicates that have been analyzed per individual. Figure was reprinted from [29], Copyright (2018), with permission from Elsevier. (**d**) Average abundance (calculated using label-free quantification) of apolipoprotein A-1, prothrombin, vimentin, osteopontin, and matrilin-1 for male (blue solid lines) and female (red dashed lines) rats (1 week—1.5-years old). Figure was adapted with permission from [148]. Copyright (2020) American Chemical Society.