Gulp. The New York Times piece DNA Evidence Can be Fabricated explains that scientists have demonstrated that it's possible to fake DNA evidence. "The scientists fabricated blood and saliva samples containing DNA from a person other than the donor of the blood and saliva. They also showed that if they had access to a DNA profile in a database, they could construct a sample of DNA to match that profile without obtaining any tissue from that person." Big gulp.
Does this change everything? Findings are presented in Authentication of forensic DNA samples, published in the Elsevier journal Forensic Science International: Genetics. The NYT quoted Dan Frumkin, lead author of the paper: “You can just engineer a crime scene.... Any biology undergraduate could perform this.”
Dr. Frumkin is with Nucleix, a company that has developed a lab test for identifying fake DNA. According to their site, the Nucleix "authentication assay distinguishes between natural and artificial DNA samples. The assay... outputs a decision whether the sample is natural or artificial. An internal validation step also controls for amplification failure due to PCR inhibitors, insufficient template DNA, etc." If their research stands the test of time, I'm guessing this will be very, very good for Nucleix investors and insiders.
Gold star. In a well-written abstract, the researchers do a good job of explaining their approach, and what they found: "the disturbing possibility that DNA evidence can be faked has been overlooked. It turns out that standard molecular biology techniques such as PCR, molecular cloning, and recently developed whole genome amplification (WGA), enable anyone with basic equipment and know-how to produce practically unlimited amounts of in vitro synthesized (artificial) DNA with any desired genetic profile. This artificial DNA can then be applied to surfaces of objects or incorporated into genuine human tissues and planted in crime scenes. Here we show that the current forensic procedure fails to distinguish between such samples of blood, saliva, and touched surfaces with artificial DNA, and corresponding samples with in vivo generated (natural) DNA. Furthermore, genotyping of both artificial and natural samples with Profiler Plus® yielded full profiles with no anomalies. In order to effectively deal with this problem, we developed an authentication assay, which distinguishes between natural and artificial DNA based on methylation analysis of a set of genomic loci: in natural DNA, some loci are methylated and others are unmethylated, while in artificial DNA all loci are unmethylated. The assay was tested on natural and artificial samples of blood, saliva, and touched surfaces, with complete success. Adopting an authentication assay for casework samples as part of the forensic procedure is necessary for maintaining the high credibility of DNA evidence in the judiciary system."
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