Emedinews : Insights on Medicolegal issues: DNA tests are run at least twice, both independent of each other

No two people, except identical twins, have the same DNA structure

·   DNA testing is done by taking DNA extracts from biological sample putting them into a gel matrix and then using probes to help extract certain markers. Human being has a unique signature that lives within every cell of our body. This signature is commonly known as DNA.

·   Testing can be done on DNA to help determine parentage, ancestry, presence of genetically based diseases and to help identify someone who may have been present at a crime scene

·   Most DNA tests are run at least twice, both independent of each other. This not only builds upon the credibility of the test but also helps ensure that no wrong data or incorrect marker analysis was performed on the first test. If any discrepancies are detected between the two tests then a new sample is used and the entire test is performed again to understand where the discrepancy may lay.

·      We get our DNA from our biological mother and biological father. Each of them contributes 50% of our chromosomes that will make up our DNA – this same DNA will stay with us for our entire lives without change. This is the very reason that makes DNA such a great choice for uniquely identifying a person.

·    Questions may arise as to how accurate DNA tests are. After all, in the past blood tests can not been as accurate as we might have hoped. They often left a bit of uncertainty or could not be conclusive in many areas. But thanks to the uniqueness of DNA almost all of these doubts can be taken away.

·     Modern testing procedures and rules for DNA analysis mean that with rare exception DNA testing results can be guaranteed to be more than ninety percent accurate for most paternity, forensic and genetically based disease analysis. However human error can come into play. A lab may mistakenly switch samples or key in data incorrectly. All of these factors are possible, but also are very rare in occurrence. If there is ever any doubt as to the authenticity or correctness of a test it can simply be performed again to confirm accuracy in another or same lab.

(Contributed by Dr Sudhir Gupta)