Wednesday, June 22, 2016

Phenotyping the next frontier for DNA and forensic analysis

DNA phenotyping is a technique that establishes a physical likeness of the person who left the sample behind, including traits such as geographic ancestry, eye and natural hair color, and even a possible shape for facial features, reported National Geographic.
In 1984 British geneticist Alec Jeffreys stumbled upon a surprising truth: He could tell people in his experiment apart solely by patterns in each person’s minced-up DNA, the genetic code we all inherit from our parents. 
Jeffreys’s discovery formed the basis of the first generation of DNA tests. Three years later Jeffreys’s lab processed DNA from a 17-year-old suspect in the rape and murder of two teenage girls in central England, and saw that it did not match DNA from semen found in the victims. Thus the first use of DNA in a criminal case led not to a conviction but to an exoneration. (The true killer later confessed, after he tried to elude DNA screening of a group of men in the area.) 
Soon other, more sensitive tests were in use, and by 1997 the FBI was employing one that looked at 13 places on the genome where stutters in the DNA code cropped up. The odds of any two unrelated people having the same 13 patterns were one in at least hundreds of billions. It was these patterns that wound up forming the basis of the FBI’s CODIS database. By the 1990s, DNA profiling was being widely used in court cases around the world—in the United States, most famously in the murder trial of O. J. Simpson. 
DNA phenotyping is a relatively recent arrival in forensic science, and some critics question how useful it will be. The facial composites it produces are predictions from genetics, not photographs. Many aspects of a person’s appearance are not encoded in DNA and thus can never be unearthed from it, like whether someone has a beard, or dyed hair. Nevertheless, Parabon, which calls its facial composite service Snapshot, has had more than 40 law enforcement organizations as customers. Human genome pioneer Craig Venter, as part of his new personalized health company called Human Longevity, is also investigating facial reconstruction from DNA, as are many academic labs. 
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