Biggest challenge in DNA analysis
Relevance
GS Paper III – Science & Tech
Context
- On June 12, 2025, Air India Flight 171 crashed in Ahmedabad killing 270+ people.
- Due to severe body disfigurement and decomposition, DNA fingerprinting was employed to identify victims.
- This case highlights the importance, challenges, and ethical dimensions of DNA-based identification in disaster scenarios.
What is DNA Fingerprinting?
- A biotechnological method that uses an individual’s unique DNA sequence to establish identity.
- Humans share 99.9% of DNA, but the 0.1% variation includes Short Tandem Repeats (STRs), which differ between individuals.
- Used in:
- Forensic investigations
- Paternity/maternity testing
- Mass disaster victim identification (DVI)
- Criminal and civil cases
What are Short Tandem Repeats (STRs)?
| Aspect | Description |
| Definition | DNA sequences of 2–6 base pairs that repeat multiple times in a row |
| Location | Found in non-coding regions of DNA |
| Inheritance | Inherited from both parents (used to establish biological relationships) |
| Variability | Highly polymorphic ➝ different in every individual (except identical twins) |
| Application | Most reliable genetic marker in forensics and DVI |
Why STRs are widely used:
- High variability among individuals
- Easy amplification using PCR (Polymerase Chain Reaction)
- Require small sample sizes
- Stable across generations
Process of DNA Profiling in Disasters
- Sample Collection
- From remains: teeth, bones, tissue, blood, nails
- From relatives: buccal swabs, saliva, blood
- DNA Extraction
- Carefully extracted from degraded or contaminated tissues
- PCR Amplification
- STR regions are amplified using PCR
- Gel Electrophoresis
- DNA fragments are separated by size and visualised
- Profile Analysis
- STR patterns are matched against reference samples or databases
- Identity Confirmation
- Identity established ➝ legal handover of remains to families
Major Challenges in DNA Fingerprinting
| Challenge | Explanation | Solution |
| 🧫 Sample degradation | Heat, fire, decomposition break down DNA | Freeze samples (-20°C), use teeth/bone, store in ethanol |
| 🧪 Contamination | Mishandling or environmental exposure | Use sterile tools, trained personnel, sealed containers |
| 🔍 Mixed DNA profiles | Common in mass disasters | Use advanced software and probabilistic interpretation |
| 💻 Data analysis errors | Misreading STR bands or PCR failure | Automation, AI tools, standardised protocols |
| 🧑⚖️ Ethical issues | Consent, privacy, data misuse | Confidential handling, ethical guidelines, legal framework |
Overcoming Challenges
- Use of advanced kits for degraded DNA (e.g., from teeth)
- Automation of analysis to reduce human error
- Adherence to international standards (e.g., INTERPOL DVI protocols)
- Training forensic personnel in collection and handling
- Development of national DNA databases (with safeguards)
Notable Case Studies
| Event | Year | Significance |
| 9/11 Terror Attacks (USA) | 2001 | Burned remains identified via STR |
| Indian Ocean Tsunami | 2004 | Thousands identified using DNA |
| Victorian Bushfires (Australia) | 2009 | Skeletonised remains analysed |
| MH17 Crash (Ukraine) | 2014 | STRs used due to body fragmentation |
| Air India Flight 171 | 2025 | Used in India’s largest aviation DVI case |
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