What’s the biggest challenge in DNA analysis? | Explained

The story so far: At least 270 people, most of them passengers, were killed on June 12 when Air India flight 171, a London-bound Boeing 787-8 Dreamliner, crashed less than a minute after taking off from Ahmedabad airport. Following the accident, deoxyribonucleic acid (DNA) analysis is being used to identify the remains of those killed. In the past week, DNA samples from victims’ family members have been collected and matched, and most remains have already been identified.

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How do DNA samples help?

DNA fingerprinting identifies individuals by analysing unique regions of their DNA. While human DNA is 99.9% identical, the remaining 0.1% includes unique sequences called short tandem repeats (STRs), which are crucial for forensic investigations. DNA profiling focuses on specific regions called genetic markers, with STRs being the preferred markers due to their variability among individuals, except monozygotic twins (identical twins).“Currently, STRs are the most widely used genetic markers for human identity determination and paternity testing. Their use makes it possible to clarify most legal and forensic cases with a generally very high degree of certainty. Identification of human remains is generally performed by comparing the genetic profile of the remains with that of first-degree relatives, usually the parents,” explained Dr. Rakesh Mishra, director, Tata Institute for Genetics and Society.