Screening for co-existence of α-thalassemia in β-thalassemia and in HbE heterozygotes via an enzyme-linked immunosorbent assay for Hb Bart's and embryonic ζ-globin chain.

We sought to demonstrate the ability of levels of Hb Bart's and ζ-globin chain quantified by enzyme-linked immunosorbent assay (ELISA) in detecting α-thalassemia in β-thalassemia and HbE heterozygotes. We developed an in-house sandwich ELISA method using monoclonal antibodies (mAbs) to Hb Bart's and ζ-globin chain, and quantified levels of Hb Bart's and ζ-globin chain in 172 and 223 anonymous blood samples of β-thalassemia and HbE heterozygotes, respectively. Genotypes of α-thalassemia 1, β-thalassemia were identified, and HbE allele was confirmed using a newly developed multiplex allele-specific PCR. The in-house sandwich ELISA method detected Hb Bart's in 6.4% of β-thalassemia heterozygotes, of which 5.2% showed detectable amounts of the ζ-globin chain. 15.2% of individuals heterozygous for HbE showed a detectable amount of Hb Bart's, and the ζ-globin chain was detected in 11.2% of this cohort. All samples having detectable amounts of Hb Bart's and the ζ-globin chain were verified to be SEA-type α-thalassemia 1. ELISA-quantified Hb Bart's and ζ-globin chain levels can be used to detect double heterozygosity of α- and β-thalassemia and of α-thalassemia and HbE. This strategy may be useful in screening for co-existence of α-thalassemia in β-thalassemia and in HbE heterozygotes, particularly in countries where α-, β-thalassemia and HbE are endemic.