New Delhi, April 24: A mammoth effort to analyse genetic variations across Indian populations has blurred the lines that separate caste and religious groups, kindling memories of a 98-year-old verse from Rabindranath Tagore.
The Indian Genome Variation (IGV) project analysed 75 genes from 1,871 people drawn from 55 diverse caste, religious and tribal communities. Scientists also expect the project to throw light on how genes influence diseases, susceptibility to infections, and response to medicines.
The study by a consortium of six Council of Scientific and Industrial Research (CSIR) laboratories and the Indian Statistical Institute, Calcutta, has provided the strongest genetic evidence yet to suggest that several populations have intermingled in India over the centuries.
Dravidian lineages have mixed with Indo-Europeans, Austroasiatics have mingled with Dravidians, and bridge populations in central India are blends of Dravidian, Indo-European and Himalayan groups.
When people move, genes move with them, said Partha Mazumder, a senior project scientist at the statistical institute in Calcutta. Genes carried by migrating humans cluster into groups, and different populations acquire some genetic distinctiveness.
The scientists consider some of the findings about genetic proximity and disease risk data as so sensitive that they have decided not to make the identities of the communities public — for now.
We had intense debates on whether to reveal the names of communities, said Mitali Mukerjee, project coordinator at the Institute of Genomics and Integrative Biology (IGIB), New Delhi.
I dont think scientists are prepared yet to understand the full social ramifications if such information is made public, Mukerjee told The Telegraph. For medical applications, we dont need names. Data about disease susceptibility genes will be made available to doctors and researchers, she said.
The study, published this month in the Journal of Genetics, has shown that some Hindu caste groups are genetically closer to Muslims in the same geographical region than to their own caste cousins elsewhere in India.
The findings show differences between caste and tribal populations, but researchers believe this is because of the ancestry and relative isolation of tribal groups.
The social hierarchy of caste groups is not fully reflected in their genetic profile, said Mazumder, whos been trying to use genetics to piece together migratory histories of populations.
The analysis has also indicated that Kashmiri Pandits and Kashmiri Muslims are genetically similar and share genetic similarities with Dravidian groups. It has also shown that some Dravidian-speaking population groups in south India have Indo-European lineage.
This opens up a number of intriguing questions about the ancestry and movement of Dravidian populations, Mukerjee said.
The map weve got shows a remarkable coincidence with what Tagore appeared to have sensed, said Samir Brahmachari, the director-general of the CSIR, who, as former director of the IGIB, served as project chairman.
Brahmachari said the study results stirred his memories of Tagores 1910 poem Bharat-tirtha that has the lines: Aryan and non-Aryan, Dravidian and Chinese... Pathan, Mughal/All have merged into one body.…
The study of genetic variations can help determine risk to disease and infections and even response to drugs.
The analysis has shown that a genetic mutation called CCR5 which provides natural protection to individuals from infection with HIV is not present or is present in low frequency in most Indian populations
In the coming months, scientists hope to use genetic variation studies to understand how genes influence risk of a range of diseases — malaria to diabetes to brain disorders.
We dont want to label communities as carriers of disease-related genes nor do we want to raise false alarms, said Saman Habib, a project scientist at the Central Drug Research Institute, Lucknow, who plans to use the data to find out why different populations respond differently to malaria.