Prenatal Diagnosis of Homozygous Alpha-Thalassemia 1 of Southeast Asian Type by Polymerase Chain Reaction

Abstract

Abstract : The association of hemoglobin Bart's (Hb Bart's) hydrops fetalis or homozygous Chalssemia of Southeast Asian type is very common in Southeast Asia especially in Thailand. Becaues of the fact that the pregnancy may be complicated by toxemia, ante-or post-partum hemorthage as well as psychological burden for the family and the mother who have to carry a nonviable fetus to term. The prenatal diagnosis of Hb Bart's hvdrops is therefore justified so that the family can be given a choice of early termination of the pregnancy. In order to identify the presence of Hb Bart's hydrops in the fetus, the collaboration study in 18 high risk pregnancies with Hb Bart's hvdrops fetalis were undertaken between February 1993 and October 1996 at Obstetric and Gynecology Department and the Hematology Division, Department of Pediatrics, Pramongkutklao Hospital, Bangkok, Thailand.

Amniocentesis was done at 16-33 weeks of gestation. DNA analysis were performed by polymerase chain reaction (PCR) using 2 techniques, 1) three nucleotide primers and 2) four nucleotide primers. After either therapeutic abortion or birth, heart blood or cord blood was drawn to confirm diagnosis by Hb electrophoresis and DNA analysis. Of 18 high risk fetuses, 6 were recognized as Hb Bart's hydrops fetalis, 7 showed the alpha-thalassema 1 trait, 1 showed alpha-thalassemia 2 trait and 4 were normal fetuses. The technique was entirely suitable for prenatal diagnosis of Hb Bart's hvdrops fetalis This technique was rapid, simple non-radioactive method, less expensive and available in most POR laboratories.