Stability of hair proteomes and proteomic genotyping with age and time

Hair, a skin appendage, is a frequently procured biological specimen from crime scenes and has been used in forensic investigations for over a century. Proteomic analysis and identification of genetically variant peptides (GVPs) in hair samples for identification purposes is a recent but an efficiently advancing tool for forensic and archeological uses. However, the hair samples exposed to environmental insults have been seen to undergo degradation to various degrees depending on the physicochemical factors the samples have been exposed to. Therefore, one would expect that evidentiary hair samples stored for longer periods of time will undergo alterations in their proteomes and hence can affect their use on long-term samples stored as case work. To determine the degree to which age of individual or age of sample can affect the hair shaft proteome or inferred GVP profile, protein profiles of hair samples were compared from individuals of different ages as well as samples collected from same individual at different time points and stored in dry environment at room temperature for 5 - 65 years.