Short Communication - Genetic heterogeneity of population structure in 15 major scheduled tribes in central-eastern India: A study of immuno-hematological disorders

Background: The aboriginal tribes of India constitute an important segment of the society in the world. Though a large number of genetic studies have been carried out in India, the genetic data of the populations in the state of Orissa are very limited, especially pertaining to the indigenous tribal people. Most of the earlier studies were restricted to either a single tribe or a few genetic markers. Data on population structure of tribal communities of Orissa pertaining to common hemolytic disorders and genetic variations are still scanty.
AIMS AND OBJECTIVES: In view of the limited data available on the tribes and the huge tribal population, a cross-section of ashram schools was investigated for immuno-hematological disorders in relation to geographical, linguistic and genetic variations.
MATERIALS AND METHODS: A cross-section of 15 major scheduled tribes in ashram schools from eight districts of Orissa was randomly studied for five hereditary immuno-hematological markers, namely, the ABO and Rhesus (D) blood groups, sickle cell hemoglobinopathy, β -thalassemia syndrome and G-6-PD deficiency, following the standard hematological procedures and techniques.
RESULTS: A preponderance of blood group B over A and low incidence of Rhesus-negative (D-) among Bathudi, Bhuyan, Kissan, Kolha, Kondh, Munda oraon, Paraja, Santal and Saora tribes was observed. The deficiency of G-6-PD enzyme was found to be quite high, varying from 5.1 to 15.9% among these scheduled tribes of Orissa. Both deficient female heterozygotes and homozygotes were encountered. Marked variation was seen in the prevalence of β -thalassemia trait, varying from 0 to 8.5%, in the aboriginal tribes. The frequency of sickle cell disorders was found to vary from 0 to 22.4% among the major tribes, but it was comparatively higher in Paraja (21.5%), Dhelki Kharia (13.7%), Gond (11.9%) and Bhatra (10.5%) tribes.
CONCLUSIONS: The study showed genetic heterogeneity and diversity with respect to above immuno-hematological genetic markers and indicated not only the inter-tribal admixture but also diffusion with other racial groups of India. Further, the heterogeneous tribal populations from Orissa were found to harbor almost all major hemoglobinopathies. This is the first comprehensive study of immuno-hematological disorders among the scheduled tribes from the state of Orissa.

Keywords
b-thalassemia syndrome, ABO and Rhesus blood groups, G-6-PD deficiency, genetic heterogeneity, Orissa, sickle cell disease, tribal populations