Clincal application and evluation of Hb Bart's levels as an early screening index for alpha-tlalassemia carriers

Objective:To evaluate Hb Bart's levels in neonatal cord blood as an early clinical diagnostic method for alpha-thalassemia carrier detdction.Methods:A total of 1006 neonatal cord blood samples collected form shaoguan Maternal and Child Health Care Hospital were screened for α-thalassemia carriers with both Hb Bart's level and molecular screening method simultaneously. The sensitivity and specificity of Hb Bart's levels method were analyzed.Results:Hb Bart's was detected in 64 out of 1006 cord blood samples, the positive rate for Hb Bart's being 6.36%.Concentrations of Hb Bart's varied form 0.70% to 98.90%. Abnormal hemoglobin variants were also found in 6 samples(0.59%). In these positive samples for Hb Bart's, α-thalassemia mutations were detected in 64 samples, but α-thalassemia genes were detected in 38 out of 906 in the negative samples for Hb Bart's. Therefore, the incidence of α-thalassemia mutation was calculated as 10.44%. The overall diagnostic concordant rate of Hb Bart's screening method for α-thalassemia was 62.1%. When α-thalassemia with - SEA αα,-ααα,αααα T,- SEA -α and αααα genotypes, the dianostic concordant rate of the method was 100%, 19.1%, 100%, 100% and 99.8%,respectively. The false positive rate for α-thalassemia alleles was 3.1% and false negative rate for α-thalassemia with -ααα mutation was up to 36.2%.Conclusion: Hb Bart's level in the cord blood used as early clinical screening for various α-thalassemia is simpler and faster, more economic and easier to perform compared with the molecular screening method, but for silent α-thalassemia carriers. this method is unreliable and imprecise.