In News:

Following the tragic crash of an Air India Boeing 787 Dreamliner from Ahmedabad to London Gatwick (June 2025), authorities have initiated DNA-based identification to match the remains of victims. In mass fatality incidents where bodies are mutilated or decomposed, DNA analysis becomes the gold standard for establishing identity.

What is DNA Identification?

DNA (Deoxyribonucleic Acid) is a unique genetic code present in almost every cell of the human body, with the exception of identical twins. It is widely used in forensic science for accurate identification, particularly in disasters where visual identification is impossible.

Sample Collection and Preservation:

• DNA begins degrading post-mortem, and the rate of degradation is influenced by:
  • Type of tissue (soft vs hard)
  • Environmental conditions (humidity, temperature)
• Hard tissues such as bones and teeth are preferred due to better preservation against decomposition.
• Soft tissues (like skin and muscle) degrade faster and, if used, must be stored in 95% ethanol or frozen at -20°C.
• In large-scale accidents, sample collection from wreckage can take weeks or even months (e.g., 9/11 took 10 months).

Reference Samples:

To match unidentified remains, reference DNA is taken from biological relatives—preferably parents or children of the victims, who share about 50% of their DNA.

Methods of DNA Analysis:

1. Short Tandem Repeat (STR) Analysis:

• Evaluates short, repeating DNA sequences that vary among individuals.
• Requires nuclear DNA, hence not suitable if the DNA is highly degraded.
• Analysis of 15+ hyper-variable STR regions can confirm family relationships with high accuracy.

2. Mitochondrial DNA (mtDNA) Analysis:

• Used when nuclear DNA is not recoverable.
• mtDNA is inherited exclusively from the mother and is present in multiple copies per cell.
• Effective for matching with maternal relatives (e.g., mother, maternal uncles/aunts, siblings).

3. Y-Chromosome Analysis:

• Targets male-specific genetic material.
• Useful for identifying remains using DNA from paternal male relatives (father, brothers, paternal uncles).
• Helpful when direct relatives are unavailable but male-line relatives exist.

4. Single Nucleotide Polymorphisms (SNPs) Analysis:

• Suitable when DNA is highly degraded.
• Analyzes variations at single base-pair locations in DNA.
• Can also match DNA with personal items like a toothbrush or hairbrush.
• However, less accurate than STR analysis.

Significance for Disaster Management and Forensics:

• DNA-based victim identification ensures scientific accuracy, aiding in closure for families, and upholding legal and humanitarian obligations.
• Modern forensic genetics has become an essential tool in mass disaster response protocols worldwide.