Hemoglobin E syndromes in Pakistani population

This was a hospital based study conducted prospectively for a period of one year extending from January 1 to December 31, 2008. EDTA blood samples were analyzed for completed blood counts and hemoglobin variants through automated hematology analyzer and Bio-Rad beta thalassaemia short program respectively. Six samples were randomly selected to characterize HbE at molecular level through RFLP-PCR utilizing MnlI restriction enzyme.During the study period, 11403 chromatograms were analyzed and Hb E was detected in 41 (or 0.36%) samples. Different hemoglobin E syndromes identified were HbEA (n = 20 or 49%), HbE/β-thalassemia (n = 14 or 34%), HbEE (n = 6 or 15%) and HbE/HbS (n = 1 or 2%). Compound heterozygosity for HbE and beta thalassaemia was found to be the most severely affected phenotype. RFLP-PCR utilizing MnlI successfully characterized HbE at molecular level in six randomly selected samples.Various HbE phenotypes are prevalent in Pakistan with HbEA and HbE/β thalassaemia representing the most common syndromes. Chromatography cannot only successfully identify hemoglobin E but also assist in further characterization into its phenotype including compound heterozygosity. Definitive diagnosis of HbE can easily be achieved through RFLP-PCR.Hemoglobin E is an important and common β-globin chain variant resulting from substitution of glutamine by lysine at codon 26 of β-globin gene (∞2β2 26Glu→Lys). Since its first description by Chernoff and his colleagues in 1954 [1], HbE was increasingly reported from several parts of the world. Hb E confers a survival advantage against Plasmodium falciparum and could be the logical explanation for its high global prevalence [2]. It is the most prevalent abnormal hemoglobin in South East Asia with its frequency approaching 60% in Northeast regions of Thailand [3,4], Laos and Cambodia [5]. Significant numbers were reported from other Asian countries such as Sri Lanka [6], North Eastern India [7], Bangladesh [8], Nepal [6], Vietnam [9]