A Lawrence Livermore National Laboratory-led interdisciplinary research team has developed the first-ever biological identification method that exploits the information encoded in proteins of human hair.
A colorized scanning electron micrograph of human hair. Image credit: Scanning Electron Microscopy Laboratory, University of Alabama at Birmingham.
Human identification from biological material is largely dependent on the ability to characterize genetic polymorphisms in DNA.
However, environmental and chemical processes can degrade DNA, limiting its usefulness over time.
“Nuclear DNA is the gold standard for human identification, but it is quite fragile,” said team member Dr. Brad Hart, a chemist with Lawrence Livermore National Laboratory.
“When the DNA molecule degrades from light, heat exposure or other environmental conditions, it becomes useless for identification.”
In contrast, protein is chemically more stable than DNA, can persist for longer periods and can be found in different tissue types, including hair, shed skin cells, bones, and teeth.
The team, led by Dr. Glendon Parker, a biochemist with Lawrence Livermore National Laboratory’s Forensic Science Center, investigated whether the protein found in human hair could offer another tool for identifying individuals in forensic or archaeology scenarios.
The scientists examined male and female hair samples for 66 European-Americans, five African Americans, five Kenyans and six skeletal remains from the 1750s and 1850s.
They have found a total of 185 hair protein markers to date, which they estimate would be sufficient to provide a unique pattern for an individual that could distinguish that person among a population of one million.
They believe that the number of individual protein markers that can be used to differentiate people could go as high as 1,000.
“Although people do not inherit proteins, they do inherit the DNA that produces their proteins,” explained team member Dr. Deon Anex, also from Lawrence Livermore National Laboratory.
“As a result, there is a link between the protein markers that we find and a person’s DNA. There are two reasons why this is particularly important: the DNA is unique to each individual and it is inherited from a person’s parents.”
The new identification technique using protein could offer another tool to law enforcement authorities for crime scene investigations and to archaeologists.
“We are in a very similar place with protein-based identification to where DNA profiling was during the early days of its development,” Dr. Hart said.
“This method will be a game-changer for forensics, and while we’ve made a lot of progress toward proving it, there are steps to go before this new technique will be able to reach its full potential.”
This work is described in a paper published in the journal PLoS ONE.
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Parker G.J. et al. 2016. Demonstration of Protein-Based Human Identification Using the Hair Shaft Proteome. PLoS ONE 11 (9): e0160653; doi: 10.1371/journal.pone.0160653
