Neonatal screening for α-thalassemia by cord hemoglobin Barts: how effective is it?

Introduction: It has long been recognized that the hemoglobin (Hb) Bart's in cord blood is an accurate indicator of alpha-thalassemia and that the level of Hb Bart's was increased accordingly with the increasing numbers of the defective alpha-genes. Methods: This study used an automatic capillary electrophoresis system to determine the Hb Bart's levels in cord blood. Molecular analyses were used to detect various genotypes of alpha-thalassemia. Results: Sixty-nine of the total 1169 newborns were found to have an increased Hb Bart's in cord blood, in whom the diagnosis of alpha-thalassemia was confirmed by the DNA analysis. The remaining 1100 newborns had no detectable Hb Bart's at birth; among these, 45 carriers of silent alpha-thalassemia were diagnosed by DNA analysis. All the 45 cases had only the - alpha(3.7) deletion genotype. Conclusion: For newborns of one alpha-gene mutation, especially for 3.7-kb deletion, the method based on Hb Bart's is inadequate and is therefore not reliable for screening.