Molecular Heterogeneity of Beta-Thalassaemia and associated Disorders in Multiethnic setting of Southern Bengal, India

BN Sarkar, Subhra Bhattacharya, Sujit Mallick, Tapas Biswas, K Das, Sikha Chatterjee, VR Rao
Anthropological Survey of India, 27 Jawaharlal Nehru Road, Kolkata - 700016, India

Introduction: Beta thalassaemia is one of the inherited genetic disorders caused by mutations of the Beta-globin gene and poses a major health and socio-economic burden in the Mediterranean region, Middle-east, Indian subcontinent, Burma and in South-east Asia. India presents an alarming picture with respect to the frequency distribution of the diseased phenotypes as well as the carriers. The double heterozygous condition like E-Beta-thalassaemia is also the commonest type of thalassaemia in eastern part of India, Burma and Southeast Asia.

Objectives: The Anthropological Survey of India, in view of severity and the limited scope for management of the disease, has initiated a community genetic approach through mass awareness and massive population-screening program as the preventive measure. The objective of the present study is to identify the Beta-Thalassaemia mutations and other abnormalities in multiethnic setting of southern Bengal.

Methods: More than 5000 unrelated individuals aged 13 to 30 years from the coastal South 24-Parganas district of West Bengal have participated in the mass screening drive for beta thalassaemia under the Community Genetics Extension Program. The methods used for the present study were CBC, HPLC, ARMS-PCR and sequencing of beta-globin gene. The haplotype patterns of the mutations were also detected by RFLP.

Results and Conclusion: The label of awareness in the studied area was very poor. Altogether 13.7% of the subjects were identified to carry abnormalities of hemoglobin in one or other forms. The IVSI-nt5-G>C was found to account for about 75% of all the mutations, followed by cd41/42 (-TCTT), cd15 (G>A) and others. In high-risk zones like eastern India this prospective premarital screening would be an ideal approach for preventing haemoglobinopathies and thalassaemic births.