Fetal hematological phenotypes of various hemoglobinopathies and demonstration of embryonic hemoglobins on capillary electrophoresis: a large cohort data from prenatal screening program.

Objectives: This study reported a large cohort of fetal blood analysis of various hemoglobinopathies.

Methods: A total of 371 fetal blood specimens were recruited. Complete blood count and hemoglobin (Hb) analysis using capillary electrophoresis were performed. Genotypes were defined by DNA analysis.

Results: Among 371 fetuses, 36 were non-thalassemic and 29 thalassemia genotypes were identified in the remaining 335 fetuses. Fetuses with β-thalassemia and Hb E traits, homozygous Hb E, and Hb E-β⁰-thalassemia had similar hematological parameters as those of non-thalassemic. However, the levels of Hb A in β-thalassemia and Hb E traits were approximately half of that observed in the non-thalassemic fetuses. As for Hb E, fetuses with a single copy of the β^E-globin gene in the Hb E trait and Hb E-β⁰-thalassemia had lower Hb E levels as compared to that of the homozygous Hb E. For α-thalassemia, fetuses with one or two α-globin gene defects had small changes in hematological parameters, but variable Hb Bart's levels were observed. Fetuses with Hb H and Hb H-CS diseases had moderate anemia, whereas those with homozygous Hb CS and Hb Bart's hydrops fetalis had severe anemia. Identification of the fetuses with Hb Bart's hydrops fetalis with various genetic interactions allows the exact re-location of electrophoretic mobilities of various embryonic Hbs.

Conclusions: This study confirmed the genetic heterogeneity of hemoglobinopathies among the fetuses and fetal blood analysis are useful for presumptive diagnosis of hemoglobinopathies. The results should facilitate a prevention and control program of hemoglobinopathies in the region.