Why in the News?
A landmark study published in the ‘Cell’ journal has sequenced the genomes of 2,762 Indians from 23 states and union territories, creating the most comprehensive genomic map of India to date.
About the Genomic Atlas:
- Overview: The Genomic Atlas is the most comprehensive genetic mapping of Indian populations, covering caste, tribe, language, geography, and urban-rural distinctions.
- Collaboration: It was conducted by Indian and international institutions, aiming to understand how ancient migrations and social structures shaped Indian genomes.
- Use of Molecular Clocks: Researchers used genetic mutations as molecular clocks to trace human ancestry and map the evolutionary history of diverse groups in India.
- Focus on Disease and Ancestry: The study explores recessive disorders, disease-linked mutations, and interbreeding with archaic humans like Neanderthals and Denisovans.
- Scope: Plans include expanding coverage to more isolated communities and building tools to track disease origins within genetically distinct Indian groups.
- Impact on Precision Medicine: It aims to improve personalised healthcare by incorporating Indian genetic diversity into global medical research.
Key Highlights of the Study:
- Discovery of New Gene Variants: Over 2.6 crore previously undocumented genetic variants were discovered, many of which are absent from international gene databases.
- Single-origin migration: Indians descend primarily from a single out-of-Africa migration ~50,000 years ago, not earlier human groups.
- Three major ancestral components:
- Ancient Ancestral South Indians (AASI) – early hunter-gatherers.
- Iranian-related Neolithic farmers – from Sarazm (~4th millennium BCE).
- Eurasian Steppe pastoralists – arrived around 2000 BCE, tied to Indo-European languages.
- Additional East Asian ancestry: Found in East, Northeast, and some Central Indian populations (e.g., 5% in West Bengal), likely post-Gupta or rice cultivation-related (~520 CE).
- Caste endogamy impacts: Long-term inbreeding within castes has led to high homozygosity, raising the risk of recessive genetic diseases.
- Archaic DNA: Indian genomes show rich Neanderthal and Denisovan segments, especially in immune-related genes like MHC, TRIM, and BTNL2.
- Unique health risks: A BCHE variant linked to anaesthetic reaction is enriched in Telangana; 7% of discovered protein-altering variants relate to serious genetic disorders.
- Every individual had at least one genetic relative in the sample—revealing extreme interrelatedness and strong founder effects, particularly in South India.
- Unmatched Neanderthal diversity: India harbours the widest variety of Neanderthal-derived genetic fragments among global populations.
| [UPSC 2021] In the context of hereditary diseases, consider the following statements:
1. Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of the egg. 2. A child inherits mitochondrial diseases entirely from the mother and not from the father. Options: Which of the statements given above is/are correct? (a) 1 only (b) 2 only (c) Both 1 and 2* (d) Neither 1 nor 2 |
