Prevalence of double heterozygotes of HbE and α-thal 1 (SEA) type in pregnancies and their partners that received antenatal care at Chiangrai Prachanukroh Hospital and reevaluated the cut-offs for differentiation

Abstract

Background In Thailand, double heterozygotes of HbE and α-thal 1 (SEA) type is common. If pregnant women carrying this genotype conceive with partners who also carry the same genotype or who are carriers of α-thalassemia 1 (SEA) type, there is 25% chance of a fetus having Hb Bart’s hydrops fetalis. This research aims to determine the prevalence of double SEA/E, compare the hematological parameters and HbE levels between pure HbE heterozygote and double SEA/E and reevaluate the cut-offs used to screen individuals with these genotypes. Methods In a retrospective study, 397 samples from individuals (partners who visited the Antenatal Care Clinic, Chiangrai Prachanukroh Hospital, Chiangrai Province, from 2017–2021) with HbE (hemoglobin typing EA) were collected. The samples were then classified as HbE with or without α-thalassemia 1 (SEA) type and RBC, Hb, Hct, MCV, MCH, MCHC, RDW and HbE level were compared between pure HbE heterozygote and double SEA/E via Student’s t-test, with a p-value of 0.05. Cut-offs were reevaluated in samples that avoided interfering with iron-deficiency anemia via the parameters of sensitivity, specificity, PPV, NPV and accuracy. Results The study revealed that the prevalence of double heterozygotes of HbE and α-thal 1 (SEA) type was 12.6%. HbE level, MCV, MCH and MCHC in double heterozygotes of HbE and α-thal 1 (SEA) type were significantly lower, whereas RBC and RDW were greater (p < 0.001). Reevaluation for cut-offs revealed that, in the group with Hb < 10.0 g/dL, combined cut-offs (MCH + HbE level) and (MCV + MCH + HbE level) for the group with Hb = 10.0–11.9 g/dL were most effective, while a single cut-off (HbE level) was most effective for the group with Hb ≥ 12.0 g/dL. Conclusions Double SEA/E were also common among pregnant women and their partners who visited Chiangrai Prachanukroh Hospital, Chiangrai, Thailand. Using appropriate cut-offs for hematological parameters and HbE levels allows pure HbE heterozygote to be distinguished from double SEA/E.