Hb A1c Determination by Capillary Electrophoresis is an Efficient Method for Detecting β-Thalassemias and Hemoglobin Variants

Abstract

Glycated hemoglobin (Hb A1c) determination by multicapillary zone electrophoresis (MZE) can additionally be used to detect Hb A2, Hb F and most common hemoglobin (Hb) variants. We assessed the effectiveness of this method for detecting β-thalassemia (β-thal), δβ-thalassemia (δβ-thal) and most common Hb variants. Moreover, Hb F/Hb A2 is evaluated as an index for discriminating between β- and δβ-thal traits. The theoretical β-thalassemia major (β-TM) birth rate in our healthcare area is calculated and contrasted with real data. A MZE technique was used for Hb A1c measurements in 27,724 patients. Previous criteria for carrier detection were established and subsequently confirmed by molecular biology techniques. Positive predictive value (PPV) was 100.0%. The prevalence of β-thal trait (including δβ-thal) was 0.34%. The most prevalent mutations (estimated per 100,000 population) were HBB: c.118C > T (57.7%), HBB: c.93-21G>A (50.5%), HBB: c.92 + 1G > A (43.3%), HBB: c.92 + 6T > C (32.5%) and HBB: c.20delA (18.0%) for β-thalassemias, and Hb S (HBB: c.20A > T) (32.5%) and Hb J-Baltimore (HBB:c.3880T>A) (28.9%) for Hb variants. We found a paradoxical result between the theoretical β-TM birth rate and real data. We calculated an optimal Hb F/Hb A2 index cutoff of 0.71 for discriminating between β- and δβ-thal traits. This method is highly cost-effective for detecting β-thalassemias and common Hb variants. Prevalence results match previous data for the Spanish population. Heterogeneity of mutations in Spain has markedly increased as a consequence of migration. The Hb F/Hb A2 index cutoff could be used to predict δβ-thal trait.