Analysis of fetal blood using capillary electrophoresis system: a simple method for prenatal diagnosis of severe thalassemia diseases

INTRODUCTION: Prenatal diagnosis of severe alpha- and beta-thalasssemia diseases is usually performed by DNA analysis. OBJECTIVE: To establish a simple method, we have evaluated the reliability of prenatal diagnosis by fetal blood analysis using automated capillary electrophoresis system. METHODS: Forty-seven fetal blood specimens collected by cordocentesis at 18-28 wk of gestation were analyzed by the capillary electrophoresis system (Sebia). Fetal DNA was analyzed for respective thalassemia alleles by PCR. RESULTS: Among 47 fetuses, 20 were at risk for the Hb Bart's hydrops fetalis. DNA analysis identified four cases of homozygous alpha degrees -thalassemia (SEA type). Hb analysis by the capillary electrophoresis demonstrated a major peak of Hb Bart's (78.4-81.3%), Hb H (0.8-1.4%) and minor peaks of presumably embryonic Hbs. No Hb F and Hb A was observed. The level of Hb Bart's was found to be 3.4-5.8% in unaffected heterozygote whereas normal fetus had no Hb Bart's. Among the remaining 27 fetuses at risk for Hb E-beta-thalassemia, DNA analysis identified 12 affected fetuses. Hb analysis showed Hb F (94.9-98.9%) and Hb E (1.1-1.8%) without Hb A in all cases. The levels of Hb A were found to be (4.3-7.2%), (1.0-5.5%) and (2.1-3.9%) in normal, heterozygous Hb E and heterozygous beta-thalassemia fetuses, respectively. Affected and unaffected fetuses could be easily distinguished. CONCLUSION: Capillary electrophoresis system is a simple and automated procedure for accurate prenatal diagnosis of severe thalassemia diseases which could readily be performed in routine setting.