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.