Decade of DNA Evidence May be Faulty

Tagged: DNA, Technology
Source: dailytech - Read the full article
Posted: 6 years 12 weeks ago

Findings could lead to appeals nationwide, if verified

"You've got the wrong man! I'm innocent!"

Many perfectly guilty criminals insist that, but what if it was true? That indeed could be true in some cases, as a new revelation casts doubt on certain verdicts in the U.S. Justice system delivered since the mid-1990s. It stems from an important finding made by a team co-led by Nickolas Papadopoulos, a Johns Hopkins University geneticist. The team discovered that DNA from tiny symbiotic bacterial-descendants called mitochondria that live in our cells and give them energy varies from tissue to tissue in the human body.

The finding is significant as mitochondrial DNA analysis was considered a proven enough technique that U.S. law enforcement has been using it as a tool to identify criminals since the mid-1990s. Mitochondrial DNA analysis was often used in the cases where the human DNA was too damaged for accurate processing (there's numerous mitochondria in a cell, so there's a better chance of accurately processing it).

The new results, set to be published today in the Mar. 4 edition of the prestigious journal Nature, indicates that possibility of false negatives might be much higher than previously thought. Also, the chance of two people having the same mitochondrial DNA goes up as well.

As Dr. Papadopoulos comments, "I wouldn’t say that it throws other results out the window, but it does throw a curve ball."

The new study used cutting edge gene sequencing equipment to analyze mitochondrial DNA from nine tissue types in two people. It found a great deal of variety of mitochondrial DNA in various tissues, much more variation than was previously thought to exist. For example, they found one DNA sequence was found in 7 percent of a person’s skeletal-muscle mitochondria, but 90 percent of their kidney mitochondria.

Dr. Papadopoulos describes, "It’s more than was thought, and was present in almost every tissue we looked at."

In order to get proper results, the study indicates, law enforcement would have to collect mitochondrial DNA from multiple regions in the suspect or victim's body.

Some aren't convinced that the results are accurate. John Planz, associate director of the DNA Identity Laboratory at the University of North Texas Health Science Center says that past studies which indicated the same thing turned out to be the result of measurement errors.

Still, if the results are validated it could lead to a major shakeup in the field of forensics, including criminal forensics. It could even lead to some appeals in the near future. And it's not the only storm brewing for DNA evidence on the horizon; other studies have also cast doubts on the validity of using DNA evidence in court (among other things, anyone who has taken an intro biochemistry or molecular biology course should be able to recognize that it would be relatively elementary for a criminal to plant DNA evidence, such as hair or dandruff, from someone they lived in close quarters with, on a victim).




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