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

Abstract

It has long been recognized that the hemoglobin (Hb) Bart's in cord blood is an accurate indicator of α-thalassemia and that the level of Hb Bart's was increased accordingly with the increasing numbers of the defective α-genes. 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 α-thalassemia. Sixty-nine of the total 1169 newborns were found to have an increased Hb Bart's in cord blood, in whom the diagnosis of α-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 α-thalassemia were diagnosed by DNA analysis. All the 45 cases had only the -α(3.7) deletion genotype. For newborns of one α-gene mutation, especially for 3.7-kb deletion, the method based on Hb Bart's is inadequate and is therefore not reliable for screening.