Monday, December 12, 2011

Human origin: India has two sets of ancestral populations, says CCMB

Syed Akbar
Hyderabad:  In a major finding that could help in tracing of
human origin and genetic basis of diseases in Indian populations, the
city-based Centre for Cellular and Molecular Biology has discovered
that Indians carry a different set of mutations in the genes
responsible for irregular lipid metabolism and type-2 diabetes.

The new finding will be useful in designing strategies to intervene or
cure diseases, says CCMB director Dr Ch Mohan Rao. The CCMB also found
that India has two sets of ancestral populations - one related to
south and west Asia, Middle East, and the Caucasus, while the other
not related to any group and restricted to south Asia. The latter
group is responsible for more than 50 per cent of the ancestry in
Indian populations.

The study was conducted by CCMB scientists led by Dr K Thangaraj in
collaboration with the University of Tartu, Estonia, the Chettinad
Academy of Research and Education, Chennai, and Banaras Hindu
University, Varanasi. The finding has been published in the
prestigious American Journal of Human Genetics. The team reported new
genome-wide data for 142 samples from 30 ethnic groups of India.

The researchers found genes like MSTN, DOK5 and CLOCK have potential
implications in lipid metabolism and type 2 diabetes. “The elements of
population structure and genes are likely to bear relevance for
medical genetic studies on populations of South Asia, which harbours
currently one-sixth of human population in the world,” they said.

Dr Mohan Rao said CCMB has been undertaking studies on population
genetics for tracing of human origin and genetic basis of diseases in
Indian populations.

India has one of the world’s fastest growing and soon greatest in
absolute terms, incidence of type 2 diabetes, as well as a sizeable
number of cases of the metabolic syndrome, both of which have been
linked to recent rapid urbanization. Even non-obese Asian Indians have
been shown to exhibit increased levels of insulin resistance compared
to European controls

“Our results confirm both ancestry and temporal complexity shaping the
still on-going process of genetic structuring of South Asian
populations.  This intricacy cannot be readily explained by the
putative recent influx of Indo-Aryans alone but suggests multiple gene
flows to the South Asian gene pool, both from the west and east, over
a much longer time span,” the scientists said.

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