New Delhi: Scientists here have completed a study mapping the genes of various ethnic groups in India, the largest such study on any population anywhere in the world that shows which groups are susceptible to which diseases and responsive to which medicines.
According to this study, salbutamol, a popular drug for treating asthma and other respiratory diseases, may not be as effective on natives of Rajasthan as it is on those from Tamil Nadu, and people in parts of Punjab, Haryana and Kashmir have a natural immunity to HIV/AIDS.
The findings have significant implications. They open up new areas of study for anthropologists, for instance, by showing that certain populations in Kashmir are more genetically closer to Keralites, than local Kashmiris.
They will help doctors and drug companies understand the genetic predisposition to diseases across the country and, eventually, help them come up with the right treatment for people of a certain genetic profile.
Genetic Landscape Of The People Of India (Graphic)
Disease Susceptibility (Graphic)
Headed by Samir Brahmachari, director general of the Council of Scientific and Industrial Research, the Indian Genome Variation Consortium (IGVC) including at least 150 scientists has mapped nearly 1,871 human genomes, sourced from 55 endogamous (pertaining to a community, clan or tribe) populations.
Though that’s just a fraction of the nearly 28,000 endogamous populations within India, scientists say that the choice of 55 populations has been done in a way to be representative of a quarter of India’s genetic diversity.
“And that’s pretty much the most comprehensive, wide- ranging study of genetic variation not only in India,” but anywhere in the world, said Mitali Mukherjee, a scientist with the Institute of Genomics and Integrative Biology, who is closely involved with the study.
The gene-mapping study identified a representative set of 75 genes, involved in cancer, ageing, eye-diseases, cardiovascular disorders, and neuro-psychiatric disorders and analyzed variations within these genes among the sample population.
For drug companies and clinical researchers, the result could mean more complex drug tests. “It’s possible for drugs to react differently even among people in the same state,” said genetics professor Seyed Hasnain, vice-chancellor, University of Hyderabad, and a genetics expert who was not part of the study group.
He added that while it wasn’t surprising to find similarities in the genetic profiles of people living in opposite corners of the country, “considering the tremendous number of migrations throughout Indian history,” most groups “maintain their genetic uniqueness, unlike populations in the United States or Europe.”
Krishna Ella, chief managing director of Bharat Biotech International Ltd, which works in pharmaceutical research, said: “The association between genes and diseases as of today is not very strong for a range of diseases. That’s why approved drugs are allowed to be distributed throughout the country. But when studies like these and the association of diseases and genes get stronger, clinical trial organizations will find it tougher.”
Until now, the only such resource available to drug firms and other researchers was the result of a worldwide project, called the International HapMap Project, which studied populations from China, Japan, Canada, the UK and the US (it doesn’t include India). “We’ve shown that HapMap studies cannot always be applied to the Indian context,” said Brahmachari.
“In fact the term ‘Indian,’ is a misnomer in population genetic studies, as it indicates the population to be homogeneous. This is evidently now untrue.”
The purpose of this study, Brahmachari added, was to develop pharmacogenics (developing customized drugs for people) in a significant way. “A host of similar studies have been outlined in the 11th Plan, and more research and funds will be allocated to link diseases, and develop medicines, specific to communities,” said Kapil Sibal, minister for science, technology and earth sciences.
The government plans its development and economic programmes over five-year periods.
The 11th Plan is for the five years up to 2012.
The study discovered that there were five major groups of people across the various communities studied, and that there was significant variation within each group.
It further discovered that there was a mix of people from more than one group in various “linguistic regions” of the country.
Rather than divide the country into geographic zones, which has no anthropological basis, the scientists broke it up into linguistic zones based on the origin of the language spoken there.
The four zones are Indo-European (includes languages such as Hindi and Marathi), Dravidian (includes languages such as Tamil and Kannada), Austro-Asiatic (dialects such as Nicobarese and Khasi), and Tibeto-Burman (Tibetian dialects and Lepcha of Arunachal Pradesh). The zones aren’t always contiguous.