GENOME SEQUENCING

GENOME SEQUENCING

WHY IN NEWS ?

• Recently the Department of Biotechnology announced that the exercise to sequence 10,000 Indian human genomes and create a database under the Centre ­backed Genome India Project is about two­-thirds complete.

MORE ABOUT THE NEWS

• About 7,000 Indian genomes have already been sequenced of which 3,000 are available for public access to researchers.

WHAT IS GENOME SEQUENCING ?

• The human genome is the entire set of deoxyribonucleic acid (DNA) residing in the nucleus of every cell of the human body.
• It carries the complete genetic information responsible for the development and functioning of an organism.
• The DNA consists of a double-­stranded molecule built up by four bases.

• While the sequence of base pairs is identical in all humans, there are differences in the genome of every human being that makes them unique.
• The process of deciphering the order of base pairs, to decode the genetic fingerprint of a human is called genome sequencing.

APPLICATIONS OF GENOME SEQUENCING

• Genome sequencing has been used to evaluate rare disorders, preconditions for disorders and even cancer from the viewpoint of genetics, rather than as diseases of certain organs.
• Nearly 10,000 diseases —including cystic fibrosis and thalassemia — are known to be the result of a single gene malfunctioning.
• In public health, however, sequencing has been used to read the codes of viruses.
• One of its first practical usages was in 2014, when a group of scientists from M.I.T and Harvard sequenced samples of Ebola from infected African patients to show how genomic data of viruses could reveal hidden pathways of transmission.
• DNA and transgenes are used to create oral plant vaccines that stimulate immunity.
• Precision medicine provides information about the genetic makeup of a patient to direct the type of treatment they receive.
• Large-scale cancer sequencing efforts such as TCGA and ICGC have catalogued somatic mutations in a variety of common cancer types.
• Most of these projects had both an exome sequencing and a whole-genome sequencing component, but due to the cost, the majority of cases got exome sequencing.
• One of the great promises of genomic research is personalized medicine: tailoring disease treatments to an individual’s genetic makeup.

GENOME SEQUENCING PROJECTS

• In 1990, a group of scientists began to work on determining the whole sequence of the human genome under the Human Genome Project.
• The Project released its latest version of the complete human genome in 2023, with a 0.3% error margin.
• This shows that genomic sequencing has now evolved to a stage where large sequencers can process thousands of samples simultaneously.
• There are several approaches to genome sequencing, including whole genome sequencing.

• The process of whole ­genome sequencing, made possible by the Human Genome Project, now facilitates the reading of a person’s individual genome to identify differences from the average human genome.

HOW DID SEQUENCING HELPED IN COVID-19 PANDEMIC ?

• In January 2020, at the start of the pandemic,Chinese scientist Yong­Zhen Zhang, sequenced the genome of a novel pathogen causing infections in the city of Wuhan.
• Zhang then shared it with his virologist friend Edward Holmes in Australia, who published the genomic code online.
• It was after this that virologists began evaluating the sequence to try and understand how to combat the virus, track the mutating variants and their intensity and spread, and to come up with a vaccine.
• To enable an effective response against COVID­19, researchers kept track of emerging variants, conducting further studies about their transmissibility, immune escape and potential to cause severe disease.
• Genomic sequencing became one of the first steps in this important process.
• Here, the purpose of genome sequencing was to understand the role of certain mutations in increasing the virus’s infectivity.

• India also put in place a sequencing framework — the Indian SARS­COV­2 Genomics Consortia (INSACOG).
• This consortium of labs across the country, was tasked with scanning coronavirus samples from patients and flagging the presence of variants known to have spiked transmission internationally.
• As of early December 2021, INSACOG had sequenced about 1,00,000 samples.

ABOUT GENOME INDIA PROJECT

• India’s 1.3 billion ­strong population consists of over 4,600 population groups, many of which are endogamous.
• Thus, the Indian population harbours distinct variations, with disease causing mutations often amplified within some of these groups.
• But despite being a large population with diverse ethnic groups, India lacks a comprehensive catalogue of genetic variations.
• Creating a database of Indian genomes allows researchers to learn about genetic variants unique to India’s population groups and use that to customise drugs.
• About 20 institutions across India are involved in the Project.

WAY FORWARD

• Within a span of only 13 years, an amalgam of public and private researchers was able to successfully complete the Human Genome Project.
• The data collected from genome sequencing of the virus will further aid in studying linkages between the variants and epidemiological waves (super-spreader events, outbreaks) of the virus.
• These scientists inspired an ongoing revolution in our fight against human disease and provided a new vision of the future of medicine-although that future has yet to be fully realized.

SYLLABUS: MAINS, GS-3, SCIENCE AND TECHNOLOGY

SOURCE: THE HINDU