HUGO study reveals India as the source of Asian genetic diversity

By: ASHOK B SHARMA

A study done by a consortium of geneticists from 10 Asian countries shows that Indian genetic diversity is the basis of other population in Asia. It says that over 50,000 years ago there was a first single stream entry of humans into India from Africa. From India the human population settled in South-East Asia and from there some of then moved to east and central Asia.

The study tends to refute the age old belief that Aryans as a distinct race who migrated from Central Asia and settled in the plains of north India. If we are believe the origin of humankind in Africa and the first outward stream of humans settling in India and thereafter spreading to other parts of Asia, including Central Asia, then they are same people who might have probably come back and resettled in India from Central Asia However, HUGO has planned to undertake further studies including Central Asia and the Polynesian Islands.

The first ever study of human genomes of Asia conducted by Human Genome Organisation (HUGO) Pan-Asian SNP Consortium also says that some of the Indian population showed evidence of shared ancestry with European population and this is consistent with the expansion of Indo-European speaking population.

This HUGO’s Pan-Asian initiative is a consortium of 90 geneticists and 40 institutions from 10 Asian nations, namely China, India, Indonesia, Japan, Malaysia, Philippines, Singapore, South Korea, Taiwan and Thailand. It collected samples from 1,928 unrelated individuals representing 73 groups of people from 10 countries and 10 linguistic lineages from member countries as well as from two non-Asian population groups of Africo-American and Caucasian ancestry.

HUGO Pan-Asia SNP Consortium study has been recently published the reputed  Science magazine (vol 326) in December 11, 2009 According to the study modern humans evolved in Africa and spread across the world, adapting locally to the selective pressures of climate, food sources and pahogens.

'Tracking genetic variations through human migrations provides clues to evolution of diseases and phenotypes. India can be a crucible for clinical trials of medicines suitable for Asian population,' said Prof Samir Brahmachari, director-general of the apex Indian scientific body, Council of Scientific and Industrial Research (CSIR). Alongwith Prof Brahmachari, Dr Mitali Mukherjee of Institute of Genomics and Integrative Biology  and Dr Partha P Majumdar, head of the human genetics unit of Indian Statistical Institute were represented in the consortium from India.

According to the study the most recent common ancestors of Asians arrived first in India. Later some of them migrated to Thailand and southwards to the land known today as Malaysia, Indonesia and also eastwards to the Philippines. The first group of settlers must have gone very far south before they settled successfully. These includes the Malay Negritos, Philippine Negritos, the East Indonesians and early settlers of the Pacific Islands. Thereafter one or several groups of people migrated North, mixed with previous settlers there and finally formed various population groups we now refer to as Austronesian, Austro-Astiatic, Tai-Kadal, Hmong-Mien and Altaic.

'This study is a milestone not only in the science that emerged, but the consortium that was formed. Ten Asian countries came together in the spirit of solidarity to understand how we related as a people and we finished with a truly Asian scientific community. We overcame shortage of funds and diverse operational constraints through partnerships, good will and cultural sensitivity,' said Prof Edison Liu, executive director Genome Institute of Singapore and President of the HUGO.

The study also reveals that more than 90% of East Asian haplotypes are found in either South-East Asian or Central-South Asian population and shows clinical structure with haplotype diversity decreasing from south to north. Furthermore, 50% of East Asian haplotypes were found in South-East Asia only and 5% were found in Centra-South Asia only, indicating that South-East Asia was a major geographic source of East Asia population.

India has recently achieved a major breakthrough in human genome sequencing. Scientists at CSIR’s affiliate organization, Institute of Genomics and Integrative Biology (IGIB)  sequenced the human genome of an anonymous Indian citizen. The human genome has 3.1 billion basepairs The team at IGIB generated over 51 gigabases of data using next generation sequencing technology, resulting in over 13x coverage of the human genome. This next generation sequencing technology used in this case enables massively parallel sequencing of millions of genomic fragments of 76 base pairs which are then mapped back to the reference genome. This humongous exercise was made possible with the CSIR supercomputing facility at IGIB.

Sequencing of a human genome requires high computational capability and technological know-how in handling sophisticated machines and analyzing huge volume of data. The first human genome sequencing initiative was conceived as early as 1984. In addition to the US, the international human genome project consortium comprised geneticists from UK, France, Germany, Japan and China. This project formally started in 1980 and sequencing was completed in 2003. India then could not be a part of the process due to lack of resources. Currently more than 14 human genomes sequences from different countries have been announced globally. With the completion of its first first human genome sequence, India is now in the league with few select countries like the US, UK, China, Canada and South Korea.

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