Rapid detection of three commonest deletional α-thalassemias in China by gap-PCR and its application to prenatal diagnosis

Objective To establish a rapid and accurate polymerase chain reaction(PCR) based methd for detection of three commonest deletional α thalassemias at the same time in China and apply it to antenatal large scale carrier screening and the prenatal diagnosis. Methods Three groups of primers were designed on basis of gaq PCR and the PCR reaction conditions were optimized on the purpose of amplifying effectively peculiar DNA fragments indicating respective genotypes of the deletional α thalassemias.A total of 6 135 Couples of pregnant women and their mates were screened preliminarily for α thalassemia determinants with hematological method, then the cases of positive phenotypes for α thalassemias was verified and prenatal diagnosis was carried out in 32 fetuses of risk of α thalassemias with gap PCR method established by us. Results Homozygous and heterozygous as well as double heterozygous of the three commonest deletional α thalassemias were successfully detected simultaneously.Seventeen and fifteen fetuses at high risk of HbBart's hydrop and HbH disease respectively were screened in 6 135 pregnant women of Zhuhai city.Prenatal diagnosis was carried out successfully by our developed PCR technique in 31 fetuses of risk of α thalassemia major.Five and four fetuses with HbBart's hydrop and HbH disease were diagnosed respectively and termination of pregnancy were offered within two weeks after diagnosis. Conclusion This easy and accurate and reproducible three PCR based assays developed in our lab is suitable for identifying α thalassemia carriers in screenings of large populations and for antenataldiagnosis of feuses at high risk of α thalassemia major.