Test can tell suspect's age from one drop of dried blood

Posted by Kate Taylor

A new test has made it possible to tell a person's age to within nine years using a just one drop of blood, in what could potentially be an important tool to catch criminals.

The technique works even on dried bloodstains years old, and could help detectives to reopen cold cases from decades earlier.

Until now, only material such as teeth or bones was of any use in determining age - and even the most careless criminals don't leave much of either lying around. But researchers at Erasmus MC decided to develop a test based on the fact that certain DNA molecules in some blood cells decrease with age.

The molecules used are residues of the immune system known as sjTREC molecules. These special DNA molecules are released in blood cells as a result of the adaptations that have to be made by newly formed specific immune cells - T cells - to recognize bacteria, viruses, parasites or possibly cancer cells. Their number decreases with age.
 
"Based on this, we developed a reliable and sensitive, but simple, test enabling prediction of the age category of the person from whom the blood droplet originated," says Manfred Kayser, professor of forensic molecular biology. "We are now trying to make the age determination using a drop of blood more accurate."

As well as helping track down unknown offenders, the method could also help identify victims of, for example, train disasters, natural disasters or bomb attacks.

"An important challenge within our field is to obtain as much relevant information as possible from biological traces that can be significant in forensic investigation and identification," says Professor Ate Kloosterman of the Netherlands Forensic Institute.

"This creative scientific study once again shows that the Netherlands is leading in the development and application of new methods in forensic DNA research.”