Familial traits, disease risks and now, Faces!


Animation of the structure of a section of DNA...

How very often do we see forensic experts on TV, nab the killer using trace amounts of DNA that were found on the carpet or victim’s clothing? While these actors convincingly make the process seem very simple and quick, it is only the people who work in the area of forensics know how difficult and tedious the entire process is. The trick is not only in getting that little amount of blood/ saliva/ skin sample from the crime scene but also having a sturdy database of DNA markers such as CODIS to compare the results against. Without a database (which, not to forget, takes years of data gathering to make), even with bucket loads of DNA to test, a forensic expert would not be able to link the the suspect to the crime scene.

But what if we told you that one could now simply get a 3D sketch of the person whose DNA was found at the crime scene. Wouldn’t that make the job of forensic experts and the cops much easier. Well, recent study published under the guidance of Dr. Mark Shriver of the Penn State University can make this very much a possibility in the near future.

To do this, Dr. Shriver teamed up with a imaging specialist, Peter Claes, from the Department of Electrical Engineering, at the University of Leuven, Belgium. Using high resolution photographs, from almost 600 volunteers, they compared these faces against a face model that had over 7000 points of reference. With similarities and differences compared, the researchers were able to identify 44 principal components which could account for 98% of variations seen between faces.

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Face Model with over 7000 points of reference
Image source: doi:10.1371/journal.pgen.1004224.g001
While the imaging work was under way, Dr. Shriver used his expertise in population genetics to correlate the presence of polymorphisms in certain genes with the variations in facial features. After preliminary research, Dr. Shriver and his team began with a data set of 50 genes that were known to play a role in generating variations in facial shape. The researchers were already aware of the impact of sex and ancestry have on our facial development and after extensive testing of DNA obtained from the volunteers, they were able to identify 24 polymorphisms* that had significant impact on development of facial features.

Advances in the field of of population genetics now allow us to broadly classify the race of the person whose DNA is found at the crime scene. Thus, forensic experts are able to provide accurate information on whether the suspect, whose DNA is tested, is either African, European, South Asian or Native American in origin. Learning from the study, forensic experts will now be able to further test the sample for polymorphisms and use the data generated from these tests to create a 3D facial map of the person. While this might still be far away from its field application, this study has opened doors to a realm of possibilities in the field of forensics. Further research might also be able to reveal additional details such as hair colour, skin tone, other unique features that might help in identification of the culprit. We might not be far away from the future, where finding trace amounts of sample at the crime scene could simply give the cops a 3D ‘mugshot’ of the culprit.

Are you reading this, writers of sci-fi TV shows?

*- Polymorphisms -  mutations in our DNA that are quite common in population but do not cause disease




ResearchBlogging.org
Claes P, Liberton DK, Daniels K, Rosana KM, Quillen EE, Pearson LN, McEvoy B, Bauchet M, Zaidi AA, Yao W, Tang H, Barsh GS, Absher DM, Puts DA, Rocha J, Beleza S, Pereira RW, Baynam G, Suetens P, Vandermeulen D, Wagner JK, Boster JS, & Shriver MD (2014). Modeling 3D facial shape from DNA. PLoS genetics, 10 (3) PMID: 24651127
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