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We evaluated the spectrum of hemoglobinopathies among the primitive tribal groups from 4 states in India. A total of 15,200 individuals from 14 primitive tribal groups were studied by automated high-performance liquid chromatography. The hemoglobin S (HbS) allele frequency varied from 0.011 to 0.120 and the β-thalassemia allele frequency from 0.005 to 0.024. It is interesting to note that a very high HbS allele frequency was observed among the Dravidian (0.060-0.120) and Indo-European (0.060-0.076) as compared with Austro-Asiatic (0.011-0.022) speaking tribal groups. Although statistical analysis of the data did not show any ethnic differences within the states, regional differences were observed between the states for both HbS and β-thalassemia traits. HbS was found to be the most common hemoglobinopathy followed by β-thalassemia. A health plan for identifying sickle-cell homozygotes in the neonatal period with proper medical intervention is desirable., (© 2013 APJPH.)

Previous studies that pooled Indian populations from a wide variety of geographical locations, have obtained contradictory conclusions about the processes of the establishment of the Varna caste system and its genetic impact on the origins and demographic histories of Indian populations. To further investigate these questions we took advantage that both Y chromosome and caste designation are paternally inherited, and genotyped 1,680 Y chromosomes representing 12 tribal and 19 non-tribal (caste) endogamous populations from the predominantly Dravidian-speaking Tamil Nadu state in the southernmost part of India. Tribes and castes were both characterized by an overwhelming proportion of putatively Indian autochthonous Y-chromosomal haplogroups (H-M69, F-M89, R1a1-M17, L1-M27, R2-M124, and C5-M356; 81% combined) with a shared genetic heritage dating back to the late Pleistocene (10-30 Kya), suggesting that more recent Holocene migrations from western Eurasia contributed <20% of the male lineages. We found strong evidence for genetic structure, associated primarily with the current mode of subsistence. Coalescence analysis suggested that the social stratification was established 4-6 Kya and there was little admixture during the last 3 Kya, implying a minimal genetic impact of the Varna (caste) system from the historically-documented Brahmin migrations into the area. In contrast, the overall Y-chromosomal patterns, the time depth of population diversifications and the period of differentiation were best explained by the emergence of agricultural technology in South Asia. These results highlight the utility of detailed local genetic studies within India, without prior assumptions about the importance of Varna rank status for population grouping, to obtain new insights into the relative influences of past demographic events for the population structure of the whole of modern India.