The Hindu : `Consanguinity main reason for susceptibility to disease'

Online edition of India's National Newspaper
Monday, Feb 25, 2002

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National

`Consanguinity main reason for susceptibility to disease'
By Our Staff Reporter

MADURAI, FEB. 24. Description of mitochondrial DNA and Y chromosome markers has made the migratory pattern of homo sapiens and the causative factors for various diseases, more clear, according to Spenser Wells, of The Welcome Trust Centre for Human Genetics, University of Oxford.

Speaking to presspersons here on Saturday, Mr. Wells said that study in genomics has brought out evidence that diseases spread along with migration. The study has also established that the main cause for affliction of various kinds of diseases was inbreeding or consanguinity, increasing the susceptibility of diseases. This could be reduced by identifying the responsible genes in order to build resistance capacity.

The homo sapiens (the modern man), he said, also evolved in Africa, just like the primitive man, over one lakh years ago and migrated to Australia through Southern India along the coast.

One population, settled in the middle-east, expanded there and further migrated to India while the other branch migrated to Central Asia. The skin colour, he pointed out, was influenced by environmental changes.

Section of the population from South India, who migrated and expanded in South East Asia, following the first wave of migration, migrated to the East, resulting in the formation of the Mongoloid race. Likewise, sections of the Central Asian population dispersed further in three different directions - towards Americas through Bering Strait, Europe and India.

Recent collaborative studies between the Madurai Kamaraj University and the University of Oxford, UK, on Non- recombinant `Y' (NRY) chromosome have generated genomic evidences to establish the reasons behind the expansion of human communities in Central Asia and their migration to America, Europe and India. The studies are in general agreement with the mitochondrial DNA haplogroup studies.

The Head of the Department of Immunology, Madurai Kamaraj University, R.M. Pitchappan, stated that the studies on genes and Human Leucocyte Antigen (HLA) had revealed that different South Indian caste groups had their own HLA profile. Expounding the theory, he said an indepth study on NRY markers on selected South Indian race had pointers to the presence of `m130' NRY marker, characteristic of the ancient, first wave of migration from Africa, revealing the migratory route from Ethiopia to Australia through South India. For instance, the Piranmalai Kallars, who are highly exposed to the risk of HLA (DRBI 1501), possess an ancient M20 NRY chromosome showing their migration from middle-east. The same can be said of the Yadhavas of Tamil Nadu (said to be the descendants of Lord Krishna), who possess high frequency of M172 NRY allele, common in the surroundings of Baluchistan in Pakistan. The Sourashtrian population of Madurai possess M17, characteristic of Indo-Iranian nomadic culture and common in Central Asia, Dr. Pitchappan added.

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