DNA Testing: Process, Utility and Challenges

Reference

On June 12, Air India Flight 171 crashed from Ahmedabad Airport to London, killing many people. After the accident, DNA analysis is being used to identify the remains of the bodies of the deceased.

About DNA Testing

• What is it: This technique is used to identify individuals by collecting DNA. It mainly compares the DNA profile of the identifiers (usually parents of the victims) with the remains of the bodies of the deceased.
  • DNA (Deoxyribonucleic Acid) is the genetic basis of organisms that carries instructions for growth, functioning and reproduction. It is passed from parents to offspring.
• STRs : Although human DNA (deoxyribonucleic acid) is 99.9% identical, the remaining 0.1% contains unique sequences called short tandem repeats (STRs).
  • These STRs are important in forensic investigation. In DNA profiling, these specific regions are targeted to identify an individual.
  • Presently STRs are the most commonly used chromosomes for human identity determination and paternity testing.
• Importance : This process is especially important when bodies are severely damaged or decayed.

DNA Testing Process

• Collection of samples: Various types of samples such as bones, blood, nails, skin and other bodily fluids are collected from the bodies of accident victims. These samples are collected by trained forensic experts to ensure that there is no contamination.
• Preservation and storage of samples: When the remains of the body are severely damaged, DNA samples are stored at a specific temperature (-20°C). Soft tissues (such as skin and flesh) are preserved in 95% ethanol.
• Analysis of DNA: Once the samples are collected, DNA is enriched using polymerase chain reaction (PCR) technique. The DNA fragments are then separated based on their size by gel electrophoresis.
• Creation of normalized DNA profile: After this, DNA is analysed using polymerase chain reaction (PCR) technique. The specific markers (STRs) of the individual are analysed with the help of a computerised system to generate a unique DNA profile.
• Matching and Identification: The generated profile is matched with other profiles stored in the DNA database to identify the individual.

Historical Use of DNA Testing

• 2004 Indian Ocean Tsunami: DNA testing was used to identify the large number of bodies after the tsunami.
• 2009 Victorian Bushfires (Australia): To identify burnt bodies.
• 2001 (9/11) Terror Attacks: DNA testing was also used to identify people killed in the terrorist attacks in New York.
• MH17 plane crash (Ukraine) in 2014: DNA technology was used to identify 298 people killed in this plane crash.

Challenges in DNA testing

• Contamination of sample: After the accident, samples may get contaminated due to various environmental factors (such as high temperature 1500°C) and runoff, which may lead to incorrect or unclear results.
• Quality of sample: The success of DNA testing largely depends on the quality of the sample. If the sample is very bad or mixed, the results are not accurate.
• Data analysis and interpretation: Analyzing and interpreting DNA profiles correctly is also a challenging task as any technical error may lead to incorrect results.
• Ethical and privacy issues: There may also be potential cases of violation of privacy and misinterpretation in DNA testing. In addition, ethical questions may arise in procedures such as paternity testing.

Way Forward

• Technological advancement: Increase the use of automated equipment and software for DNA analysis.
• Training: Provide regular training and education to forensic experts.
• Standardized protocols: Follow Interpol's Disaster Victim Identification (DVI) guidelines.
• Awareness: Educate the public and officials about the role of DNA analysis in disaster management.
• Financial investment: More investment in forensic labs and equipment.