Studies on molecular spectrum of beta thalassemia among residents of Chennai

Beta thalassemia is caused by a mutation in the human beta globin gene. More than 400 causative mutations have been characterized in the Hemoglobin Subunit Beta (HBB) gene. These causative mutations are present in the beta globin gene or the regulatory region. Though more than 400 causative mutations of HBB region have been described, rare and novel mutations are being reported in studies indicating the need for characterization of mutations in all regions and information regarding the same should be made available for successful implementation of prenatal diagnosis. The study aims to characterize the spectrum of beta thalassemia mutations in beta thalassemia heterozygous among residents of Chennai. A total of 5,207 cases were screened for beta thalassemia heterozygous by HPLC method. 387 beta thalassemia heterozygous identified by HPLC method were subjected to molecular DNA analysis by ARMS PCR technique and DNA Sanger sequencing for the characterization of causative beta thalassemia mutations. In the present study molecular characterization of beta thalassemia mutations revealed 30 different mutations with a high prevalence of IVS 1-5 (G-C) mutation, five new rare mutations viz., IVS II-1 (G>T), CD 37 TGG-TGA, IVS II 781 (C-G), CD114 CTG-CCG and Poly A (A-G) were diagnosed and reported first in India. One novel beta thalassemia mutation HBB.c319DelC was detected in the study. The diagnostic outcome of detecting the causative mutations for beta thalassemia imposes strong resources for developing easy and cheaper methods for prenatal diagnosis which will reduce the burden of disease.