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Eye and Hair color of unknown offenders is no longer a secret (2013-10-31)

A new forensic technique called Hirisplex will soon allow investigators to predict certain physical characteristics of suspects, like their hair and eye color, after analyzing traces of DNA that were left at the crime scene.

 


 

This type of testing, originated in forensic biology, is called Forensic DNA Phenotyping (FDP). FDP allows police investigators to narrow down a large group of possible suspects. The BBC reported that according to Prof, Manfred Kayser, Chair of the Department of Forensic Molecular Biology at Erasmus MC Erasmus University Medical Center in Rotterdam, the Netherlands, who led the study, tools such as Hirisplex could be useful in those cases where the perpetrator is completely unknown to the authorities. Prof. Kayser said the test "includes the 24 currently best eye and hair color predictive DNA markers. In its design we took care that the test can cope with the challenges of forensic DNA analysis such as low amounts of materia...The test is very sensitive and produces complete results on even smaller DNA amounts than usually used for forensic DNA profiling... For our research we made use of the DNA and hair color information of hundreds of Europeans and investigated genes previously known to influence the differences in hair color. We identified 13 'DNA markers' from 11 genes that are informative to predict a person's hair color."

The test system includes the six DNA markers previously used in a test for eye color known as Irisplex, combining them with predictive markers for hair.
The authors of the study used Hirisplex to predict hair color phenotypes in a sample drawn from three European populations.
On average, their prediction accuracy was 69.5% for blonde hair, 78.5% for brown, 80% for red and 87.5% for black hair color.

This new DNA approach even allows differentiating hair colors that are similar, for example, between red and reddish blond, or between blond and dark blond hair. The necessary DNA can be taken from blood, sperm, saliva or other biological materials relevant in forensic case work.

Prof. Ate Kloosterman of the Department of Human Biological Traces at the Netherlands Forensic Institute (NFI) said: "... These researchers have previously published articles on predicting eye color and estimating age on the basis of DNA material. This type of objective information can be used to refine the description of an unknown but wanted person. This new development results in an important expansion of the future DNA toolkit used by forensic investigators to track down unknown offenders."

The Erasmus MC research was made possible by subsidies granted by the Netherlands Forensic Institute (NFI) and the Netherlands Genomics Initiative (NGI) / Netherlands Organization for Scientific Research (NWO) in the framework of the Forensic Genomic Consortium Netherlands (FGCN).

For more information
New Forensic Tests Predicts Eye and Hair Color of Unknown Suspects

Branicki W, Kayser M et al. (2011). Model-based prediction of human hair color using DNA variants. Human Genetics; DOI 10.1007/s00439-010-0939-8

FSI Forensic Science International: Genetics
The HIrisPlex system for simultaneous prediction of hair and eye colour from DNA

Bona fide colour: DNA prediction of human eye and hair colour from ancient and contemporary skeletal remains.

MDN

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