Alpha thalassaemia in tribal communities of coastal Maharashtra, India

BACKGROUND & OBJECTIVES In a routine community health survey conducted in adult Adivasis of the costal Maharashtra, microcytosis and hyprochromia were observed in more than 80 per cent of both males and females having normal haemoglobin levels suggesting the possibility of α-thalassaemia in these communities. We conducted a study in Adivasi students in the same region to find out the magnitude of α-thalessaemia. METHODS The participants (28 girls and 23 boys) were 14-17 yr old studying in a tribal school. Fasting venous blood samples (5 ml) were subjected to complete blood count (CBC), Hb-HPLC and DNA analysis using gap-PCR for deletion of -α3.7 and -α4.2, the two most common molecular lesions observed in α-thalassaemia in India. RESULTS Microcytic hypochromic anaemia was observed 50 and 35 per cent girls and boys, respectively. Iron supplementation improved Hb levels but did not correct microcytois and hypochromia. m0 ore than 80 per cent non-anaemic students of both sexes showed microcytois and hypochromia. DNA analysis confirmed that the haematological alterations were due to α-thalassaemia trait characterized by deletion of -α3.7. Majority (>60%) of the affected students had two deletions (-α3.7/-α3.7 genotype α+ thalassaemia. INTERPRETATION & CONCLUSIONS This is perhaps the first report on the occurrence of α-thalassaemia in tribal communities of coastal Maharashtra. Very high (78.4%) haplotype frequency of -α3.7 suggests that the condition is almost genetically fixed. These preliminary observations should stimulate well planned large scale epidemiological studies on α-thalassaemia in the region.