Better Than DNA: LLNL Collaboration Yields New Forensic Technique to Identify People Using as Little as One Hair

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In an important breakthrough for the forensic science community, researchers have developed the first biological identification method that exploits the information encoded in proteins of human hair.

Scientists from Lawrence Livermore National Laboratory (LLNL) and a Utah startup company have developed the groundbreaking technique, providing a second science-based, statistically validated way to identify people and link individuals to evidence in addition to DNA profiling.

The new protein identification technique will offer another tool to law enforcement authorities for crime scene investigations, as well as archaeologists. The method can detect protein in human hair more than 250 years old.

With further development, the researchers believe they could use protein markers to identify a single individual from as little as one human hair.

"We are in a very similar place with protein-based identification to where DNA profiling was during the early days of its development," said LLNL chemist Brad Hart, director of the Lab's Forensic Science Center.

"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."

The team, which comprises LLNL scientists; a researcher with Utah-based Protein-Based Identification Technologies, LLC; and collaborators and advisors from seven universities, examined hair samples from men and women of various ethnicities, as well as some skeletal remains. Their results appear in PLOS ONE, a San Francisco-based, peer-reviewed, online scientific journal.

The researchers have found 185 protein markers so far, and believe that as many as 1,000 markers could exist. Each person's number of hair protein markers, combined with their pattern of protein markers, is unique.

The scientists are now studying ways to identify people using protein markers from other tissue types, such as shed skin cells, bones and teeth.

Using their current sample sizes, the researchers can already find enough to distinguish one person among a population of 1 million.

This new technique may be able to produce results that DNA testing cannot.

"Nuclear DNA is the gold standard for human identification, but it is quite fragile," Hart said. "When the DNA molecule degrades from light, heat exposure or other environmental conditions, it becomes useless for identification."

Proteins are chemically more robust than nuclear DNA—as proven when the researchers found protein markers in human hair from six skeletal remains taken from cemeteries in the greater London area dating back about 150 to 250 years.

Proteins are long molecular chains formed from amino acids, the basic building blocks of life. DNA is the pattern or template the body uses to produce proteins.

The scientists used protein markers known as single amino acid polymorphisms (SAPs), which are variants in the proteins resulting from amino acid substitutions that stem from DNA mutations.

The team's research kicked into high gear in 2013 when biochemist Glendon Parker, the inventor of the protein identification concept and then an associate professor at Utah Valley University, came to work at LLNL.

"Glendon's clever invention was to realize that the uniqueness of SAPs could be used to identify individual people, and the robustness of the technique relies on its link back to DNA," said LLNL chemist Deon Anex.

Although people do not inherit proteins, they do inherit the DNA that produces their proteins.

"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," Anex said.

The identification process currently takes about 2½ days to complete and will likely be cost-competitive with similar technologies, according to Anex.

"The discovery phase has been quite complex, but once the technique is established, we believe it can be made into a routine procedure for use in crime labs."

The researchers are seeking to establish a set of 90-100 protein markers that could distinguish an individual among the world's population using a single hair.

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