Diagnosis of common hemoglobinopathies among South East Asian population using capillary isoelectric focusing system

We have evaluated an automated capillary isoelectric focusing (cIEF)-based Hb analyzer in diagnosis of hemoglobinopathies commonly found among South East Asian population.

Study was performed on a cohort of 665 adult Thai subjects and 13 fetal blood specimens obtained at routine thalassemia diagnostic laboratory. Hb analysis was performed using the cIEF system. Thalassemia genotypes were defined by DNA analysis.

The system revealed satisfactorily within-run and between-run precision for quantitation of Hb A₂ and Hb E (CV: 0.02-0.09%). The reference ranges of Hb A₂ and Hb E were 2.6-4.0% and 25.7-33.1%, respectively. The system identified the cases of β-thalassemia and Hb E disorders correctly. Several thalassemia genotypes and Hb variants were identifiable. However, Hb Constant Spring was separated closely to Hb A₂ and Hbs Bart's and H were relatively difficult to be reported due to interfering peaks separating at the same regions. Prenatal diagnosis by fetal blood analysis was found to be accurate for Hb Bart's hydrops fetalis and Hb E-β⁰ -thalassemia disease.

The cIEF system could accurately diagnose β-thalassemia and Hb E carriers and demonstrate many Hb variants found in the region. The system cannot report Hb A₂ in the presence of Hb E whereas Hbs Lepore and F are comigrated. Diagnosis of α-thalassemia disease based on Hb H and Hb Bart's might be difficult.