Genetic Fingerprinting

The world has seen a revolution in crime detection since the introduction of fingerprint recognition technology in the 19th century. But today we are not going to talk about the process of physical fingerprinting, we are going to talk about another feature that is unique to every individual. The DNA. Well DNA fingerprinting can be used to identify an individual beyond all reasonable doubts. Let’s see how.

Genetic Fingerprinting small

Genetic Fingerprinting big

The whole process of Genetic Fingerprinting analysis to identify a specific individual involves a lot of chemical processes. The first step is a collection of a buccal swab (a non-invasive way to collect cheek cells on a swab) or in case of non-availability of such a sample a blood stain, a drop of saliva or semen can also be used. This is called the collection of DNA sample. After collection of the sample, there are several different processes available for further processing.

The first method used to analyze the sample is the Restriction Fragment Length Polymorphism.[1] This technique is a laborious one with a requirement of a large amount of DNA that generally is unavailable at any crime scene. So the solution is Polymerase Chain Reaction (PCR) Analysis.[2] What is PCR analysis? Let’s see.

GENETIC FINGERPRINTING

PCR analysis is a technique developed by Kary Mullis in the year 1983 it works as a Xerox machine for our gene of interest. This technique, once fed with the required sample magnifies the sample ~10000 times. So the amplified amounts of DNA then can be used for further studies based on separation of the strands of DNA as per mass on a gel. The separated strands are then compared with similarly separated strands of DNA from the suspects. You find a match and you find your criminal. The process of PCR involves mimicking the biological process of DNA replication but it is specific to the gene of our interest.

The DNA once obtained and separated can then be compared to the vast criminal databases of DNA around the world. Though this facility is yet to be available in India, the United Kingdom and the United States of America maintains databases like National DNA Database and Combined DNA Index System respectively. All the criminals that are convicted in these countries have their DNA recorded in these databases. Recent legislation in the United States also asks for storing of Genetic Fingerprinting information of suspected terrorists.

The whole system of Genetic Fingerprinting identity makes identifying a person a confirmed and easy process. Hence is a powerful tool for forensics.

Sources:

https://www.ncbi.nlm.nih.gov/projects/genome/probe/doc/TechRFLP.shtml

https://www.ncbi.nlm.nih.gov/probe/docs/techpcr/

Article By
Swarnendu Ghosh