[Prenatal gene diagnosis of alpha-thalassemias].

OBJECTIVE

To study the value of polymerase chain reaction (PCR) in prenatal diagnosis of alpha thalassemias.

METHODS

Amniotic fluid prenatal gene diagnosis with polymerase chain reaction was carried out on eleven fetuses whose parents are both heterozygotes with alpha-globin gene deficiency. A DNA fragment of 224bp in the production means normal alpha-globin gene sequence, while a 630bp fragment indicated the alpha-globin gene deficiency. Both 224bp and 630bp fragments in the same sample means heterozygote.

RESULTS

Three of the 11 fetuses (one pregnancy was twin) were with normal alpha-globin gene sequence, while 4 were homozygotes and the other 4 were heterozygotes. For the 3 fetuses with ascitic fluid under ultrasound examination, 2 were homozygotes and the other one was heterozygote by gene diagnosis. Two of the 4 homozygotes from induced abortion were typical Bart's syndrome, one was edema in the whole body and the other one with short limbs and abdominal hernia.

CONCLUSION

The method of PCR in prenatal diagnoses for detection of alpha-thalassemias is simple, accurate and rapid.