What is DNA fingerprinting and how is it done?

What is DNA fingerprinting and how is it done?
It is a technique for identification of an individual by examining their DNA.

The Rajiv Gandhi Centre for Biotechnology (RGCB) in Thiruvananthapuram is carrying out DNA fingerprint examination to identify the bodies of fishermen found from the sea after the Ockhi storm.

What exactly is DNA fingerprinting? And does it look like crime scene investigations in TV shows?

What is DNA fingerprinting?

It is a technique, for identification of an individual by examining their DNA.

DNA, or Deoxyribonucleic acid, is the basic building block of life. This component in cells contains all the information about an organism and it also helps transfer the characteristics to the next generation.

The DNA of each individual is composed of Bases [Adenine (A), Thymine (T), Guanine (G), and Cytosine (C)], Sugar and a Phosphate. Two bases link to each other using hydrogen bonds to form base pairs.

“Every human has three billion such base pairs. Though 99.7% of the make up is similar between any two people; there is a 0.3% difference which accounts to almost 10 million different base pairs. By examining this we can identify the relation between two people. There is a 50% match between a child and his/her father or mother. Between siblings it can range anywhere between 25% to 75%. Monozygotic twins show a 100% match,” explains Dr. Madhusudan Reddy, staff scientist and in-charge at Lab of DNA Fingerprinting Services, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad.

Can DNA fingerprinting be done only with blood samples?

Blood, bones, hair with root, saliva, semen, teeth, and tissue can also be used to study the DNA.

“We have received the bone and sternum (breast bone) as reference sample for identification of the fishermen. The relatives of the missing person would be asked to come and provide blood samples for DNA study. We will compare the DNA to get a match,” says an official who wished not to be named from regional facility for DNA fingerprinting at RGCB.

How is DNA fingerprinting done?

The DNA is isolated from the available sample. Each type of sample has a specific protocol for isolation. The DNA fragments are then multiplied using a reaction called Polymerase Chain Reaction (PCR).

One small DNA fragment can become a thousand to million copies. This amplified DNA sample then undergoes a technique called gel electrophoresis, which splits it into different visible bands. The band pattern formed by an individual’s DNA is unique. The bands of two or more DNA samples can then be compared using software.

What are its uses?

DNA fingerprinting can be used to resolve disputes of maternity/paternity.
DNA fingerprinting can be used to resolve disputes of maternity /paternity | Photo Credit: Wikimedia Commons

- For criminal identification

- To resolve disputes of maternity /paternity

- To identify mutilated remains

- In cases of exchange of babies in hospital wards,

- In forensic wildlife (The arrangement of the nucleotides is unique to any living form (except identical twins) be animals, plants, or microbes.)

Can anyone get their DNA checked with their parents?

The official from RGCB explained that to resolve parental disputes you need a court order and will be done in the supervision of authorities from police and court.

Are there any laws in India regarding DNA fingerprinting?

In July, 2017 the law commission of India drafted a Bill for the use and regulation of DNA-based technology called the Human DNA Profiling Bill.

As there are currently no legal mechanisms for identifying missing persons and victims of disasters, the new Bill seeks to regulate human DNA profiling and establish standard procedures for DNA testing.