Key Determinants of Phenotypic Heterogeneity of Hb E/β Thalassemia: A Comparative Study from Eastern India.

HbE Beta thalassemia is phenotypically very diverse disease. We aim to study role of various genetic factors in determining severity of this disease. 243 diagnosed cases of HbE Beta thalassemia were included in this study. Patients were divided in two arms-transfusion dependent and non-transfusion dependent arms. Various factors (percentage of haemoglobin F, hemoglobin E, type of Beta mutation, Xmn1 polymorphism, alpha deletion, HPFH mutation) were evaluated in these patients. Xmn1 polymorphism (homozygous and heterozygous), presence of HPFH mutation and alpha deletion were more prevalent in NTDT arm versus TDT arm (p value < 0.001). Higher prevelance of severe beta mutation IVS 1-5 (G → C) mutation {64(61.54%) vs 38(27.34); p value < 0.001} was found in TDT arm when above factors were excluded from analysis. Higher mean haemoglobin F and mean Hemoglobin E percentage was associated with NTDT arm (p value < 0.001). Various factors (hemoglobin F and E percentage, Xmn1 polymorphism, HPFH mutation, alpha deletion and IVS 1-5 Beta mutation) were identified to affect severity of this cohort.