Screening for alpha-thalassemia-1 heterozygotes in expecting couples by the combination of a simple erythrocyte osmotic fragility test and a PCR-based method

To develop a simple method for the prospective identification of couples at risk of homozygous alpha-thalassemia-1 (Hb Bart's hydrops fetalis) in pregnancy. Antenatal care (ANC) women and their husbands were analyzed using a simple erythrocyte osmotic fragility (EOF) test and a PCR-based method for the detection of the mutation leading to alpha-thalassemia-1 of the Southeast Asian type (SEA). Heterozygosity for the alpha-thalassemia-1 (SEA) deletion was found to correlate with an EOF value <60%. For a prospective screening, ANC women and their husbands are analyzed with the EOF test and only those having a value <60% were further checked by PCR. Of 2,769 cases analyzed during a 6-month period, 24 couples in which both partners are heterozygotes could be identified for genetic counseling and prenatal diagnosis. The application of the EOF test decreased the workload for PCR by approximately 80%. Prospective screening for alpha-thalassemia-1 (SEA) heterozygotes in northern Thailand is becoming easier to realize by the combination of EOF test and PCR.