Aberrant Heterosis In Hemoglobinopathies With Special Reference To Beta-Thalassemia And Structurally Abnormal Hemoglobins E And S In Orissa, India
Corresponding Author:BALGIR R S
The population of India exhibits a wide range of genetic heterogeneity and, ecological and biological diversity including the reservoir for occurrence of a large number of abnormal hemoglobins and thalassemias in the world. Orissa state has nurtured ecological, cultural and genetic diversity of hemoglobinopathies, which has become a major genetic and public health problem in both tribal and nontribal inhabitants. Prospective studies are lacking in India. In Orissa, prospective studies of referral index cases of hemoglobinopathies provide most valuable data for analysis with respect to introspection and re-evaluation from research point of view. Intravenous blood samples were collected after obtaining informed consent from each index case of double heterozygosity for hemoglobinopathies. Background data of each individual were recorded like age, sex, caste, place of origin, reproductive history, consanguinity, etc. Twelve index cases of sickle cell-β-thalassemia and 9 index cases of hemoglobin E-β-thalassemia with anemia were subjected to detailed hematological and family genetic investigations. Routine standard hematological and biochemical investigations were carried out. This study highlights the rare occurrence of double heterozygosity of abnormal hemoglobins, i.e. Hb D, E and S with β-thalassemia mutation for the first time from Orissa. Study showed that index cases with Hb E-β-thalassemia and sickle cell-β-thalassemia manifest variable clinical, hematological and prognostic profile. High levels of fetal hemoglobin in patients reduce the severity of clinical symptoms in some but not in others. β-thalassemia or Hb E/S carrier mothers during their reproductive life either had spontaneous abortions or neonatal deaths. Aberrant heterosis for hemoglobinopathies such as occurrence of β-thalassemia mutation with structurally abnormal hemoglobins (Hb S and Hb E) is a rare entity, but occurs with severe clinical manifestations only in those areas or communities where abnormal hemoglobins and β-thalassemia are highly prevalent. This study provides for the first time a comprehensive database on the occurrence of double heterozygosity, testifying the genetic diversity and ethnic admixture in Orissa, India.