[Direct genotyping and antenatal diagnosis of deletional alpha-thalassemia of the southeast Asian type by polymerase chain reaction technique].

OBJECTIVE

To study the gene of deletional alpha-thalassemia of the Southeast Asian type (SEA) and to perform the antenatal diagnosis.

METHODS

A new method of polymerase chain reaction technique using three primers bridging the breakpoints was carried out for carrier detection and antenatal diagnosis of deletional alpha-thalassemia of the Southeast Asian type. A DNA fragment of about 630bp in size was amplified in case of--SEA alleles, while a 224 bp fragment was amplified in samples without the deletion. Homozygotes, heterozygotes, and normal subjects could be clearly distinguished with the present method.

RESULTS

We used this method in the genotyping and antenatal diagnosis of 10 high risk pregnancies of alpha-thalassemia. 2 homozygotes, 4 heterozygotes, and 4 normal infants were found.

CONCLUSION

The present method is simple and rapid in detection of carriers and antenatal diagnosis of the alpha-thalassemia of southeast Asian type.