Despite making considerable economic growth in recent times, South Asia is in deep crisis mainly because of its ‘conservative’ social culture. A recent study has revealed that the region is rife with undiscovered genetic disease.
According to the study conducted by the Centre for Cellular & Molecular Biology (CCMB) and published in ‘Nature Genetics’ journal on July 17, most South Asian linguistic races and caste groups have a high vulnerability for ‘population-specific’ diseases. Out of 263 unique South Asian groups studied, around 81 have a large number of recessive diseases.
In South Asia, inter-caste or inter-tribe marriages are rear phenomenon. Even, some groups in India, Pakistan, Bangladesh, Sri Lanka, Nepal and Bhutan prefer marriages within a family. Although such culture shows the existence of a strong community feeling in the region, researchers opine that marriages within a caste or tribe or group can lead to genetic abnormalities in offspring. They argue that the possibility of genetic diseases increases because of similar DNA stretch in case of repeated marriages between people of same group or tribe for generations after generation.
Senior CCMB scientist Dr Kumarasamy Thangaraj has said that the possibility of ‘founder event’ is much higher in case of same-caste or same-tribe marriages. Founder event is a genetic problem that occurs when a new population starts from a small number of individuals. CCMB researchers also found similarities in the structure of DNA among members of a particular community in the Indian sub-continent thanks to marriages between people of same castes, tribes and communities. As a result, the risk of ‘recessive gene disorder’ (genetic problems received from father or mother) is much higher in this part of the world.
Researchers at Hyderabad-based CCMB prepared the report only after assessing the blood samples of 2,800 participants from 275 different castes and groups. Dr Thangaraj said that out of 80 groups, identified for having high ‘Identity-By-Descent’ (IBD) score, around 14 groups have an estimated size of over one million people. Gujjars in north-western Indian province of Rajasthan, Baniyas in northern province of Uttar Pradesh and Pattapu Kapus in southern province of Andhra Pradesh have got high IBD score. It means they carry certain gene mutations responsible for diseases to future generations, stressed Dr Thangaraj.
Meanwhile, social scientists have expressed serious concern over the report, urging South Asian people to discourage age-old cultural practices that promote marriages within a particular community. David Reich, a geneticist at Harvard Medical School, has welcomed the proposal. He said that it is important to change cultural norms in order to encourage marriages between members of different groups, castes, sub-castes and tribes especially in urban areas, where gene flow between populations has been restricted for millenniums.