CRACKING INDIA'S GENETIC CODE

India’s largest-ever genomic study has identified genetic variants unique to the country, marking a crucial step in closing a longstanding gap in global genomics research.

- By Ajay Sukumaran

The preliminary findings, published last week in Nature Genetics, come from the GenomeIndia project—a nationwide effort to map the country’s vast genetic diversity.

Launched in January 2020, GenomeIndia brought together over 100 researchers from 20 institutions to conduct whole genome sequencing—a technique by which the sequence of the building blocks of DNA, known as nucleotides, is decoded—across a broad swathe of India’s population. The study analysed DNA from 10,074 individuals, drawn from a total of 20,000 blood samples collected from 83 population groups—both tribal and non-tribal.

Despite being home to more than 4,600 distinct ethnic groups, India’s representation in global genomics databases has long been lacking. The project aims to generate vital data on the genetic makeup of the Indian population, with implications for better understanding of health and disease patterns unique to the region.

A human genome has 3.2 billion base pairs, or sequences formed by the four nucleotides [adenine (A), cytosine (C), guanine (G) and thymine (T)]. These pairs are organised into long molecules of DNA called chromosomes of which there are 23 pairs—22 of these are called autosomes and one pair comprises the sex chromosomes which decide the individual's sex. Typically, two individuals can differ by 0.1 to 0.4 per cent of their genome, which means there will be differences in a few million positions in their DNA code.