Can Trimodal Distribution of HbS Levels in Sickle Cell Traits Be Used To Predict the Associated Alpha-Thalassemia For Screening Cases in Central India?

BACKGROUND Until now, trimodal distribution of HbS has been seen by six different studies in the world when associated with alpha-thalassemia with confirmation by corresponding alpha-genotyping studies. The RBC indices reduce as alpha-globin genes reduce in sickle cell trait (SCT) patients, which decreases the extent of intra-vascular sickling and thus betters the clinical course of the patients. This is a pioneer study conducted on Central Indian poor population to use the already proven six studies to screen associated alpha-thalassemia in SCT patients thus, circumventing the much costlier alpha-genotyping studies. Moreover, it aimed to study the haematological parameters in such cases. METHODS The study was performed at RHDMC, IGGMC, Nagpur, India from 2003 to 2012. The sample population was suspected cases of haemolytic anaemia. CBC and RBC indices were obtained by a cell analyzer. The sickle solubility test positively screened cases were confirmed by agar-gel haemoglobin electrophoresis at pH 8.6. Finally, quantitative assessment of haemoglobin variants was performed by HPLC. RESULTS Out of total 5819 cases over ten years, 933 cases were sickle heterozygotes. Overall, 180/933 subjects were predicted to be homozygous alpha-thalassemia and 338/933 were heterozygous alpha-thalassemia, based on trimodal distribution of HbS. CONCLUSION Genotyping is costlier for majority of the poor non-affording patients in Indian government set-ups, so this study is suitable to screen for associated alpha-thalassemia in SCT patients.