Context: DNA Profiling has been an important tool in solving cases involving forensic science, medical investigations and familial disputes. However, the technology also raises some concerns about its ethical implications and privacy breaches.
Relevance of the Topic: Prelims- DNA Profiling: Applications & Challenges
What is DNA Profiling?
- DNA profiling/DNA Fingerprinting is the technique used to identify individuals by analysing the unique patterns in their DNA.
- The process involves analysing the Short Tandem Repeats (STRs) which are highly specific to each individual (except identical twins).
The Basics of Cell and DNA:
- Each cell in the human body has 23 pairs of chromosomes (46 total chromosomes).
- Chromosomes are thread-like structures made of DNA and proteins, found in the nucleus of cells.
- One chromosome of each pair is inherited via the mother’s egg and the other via the father’s sperm.
- DNA (deoxyribonucleic acid) is a molecule that carries genetic information. It is composed of four chemical bases: adenine (A), cytosine (C), guanine (G), and thymidine (T).
- Base-pairing: A pairs with T, and G pairs with C, to form a double-helical structure.
- The human genome consists of 3.2 billion base-pairs across 23 pairs of chromosomes. At several locations in the genome, some short DNA sequences are repeated multiple times, called short tandem repeats (STRs).
- For example, one strand of an STR locus might have multiple repeats of GGCCA (GGCCAGGCCAGGCCA…).
- The DNA profile of a person is simply the number of times these sequences are repeated. The number or pattern of repetition is unique to each individual, which can be analysed by DNA profiling.
How is a DNA Fingerprint produced?
- Isolation: Extraction of DNA from a biological sample (E.g., blood, hair, saliva, semen etc.)
- Fragmentation: Break the DNA into smaller pieces using enzymes.
- Amplification: Make multiple copies of the DNA fragments by Polymerase Chain Reaction (PCR).
- Separation: Arrange DNA fragments by size using techniques such as gel electrophoresis.
- Comparison: Match the DNA profile to reference samples of DNA for identification.
Applications of DNA Profilling:
- Paternity determination.
- Criminal forensics (help solve crimes using DNA present at crime scene).
- Identification of victims in mass disasters.
- Establishing donor-recipient compatibility in organ transplants.
- Identification of alleles associated with particular genetic disorders (E.g., cystic fibrosis)
- Compare different species for classification purposes.
Challenges associated with DNA Profilling:
- Cannot be used to identify identical twins.
- Reliability of DNA profiling depends on quality of the sample, expertise in laboratory analysis. The process is not infallible and various factors (like sample contamination, degradation, or mishandling) can impact the results.
- Storage of DNA profiles can be an invasion of privacy, and risk of theft of DNA profiles from a database.
- Risk of Racial and Communal profiling.