α-Thalassemia incidence in southern Thailand by restriction endonuclease analysis of globin DNA from placental blood at Songklanagarind Hospital

Abstract

The incidence of α-thalassemia has been studied previously based on the levels of Hb Barts' in cord blood. This method is an inadequate indicator of α-thalassemia. Thus in this study we use DNA analysis to get more accurate data. Hb Barts' was detected in placental blood samples from 15.5% ot 375 infants born at Songklanagarind Hospital. The white blood cell DNA of 300 samples was studied for α-globin gene deletions by hybridization of DNA fragments digested by the restriction endonuclease Eco RI with specific 32P-labled ζ-globin gene probe. The incidence of α-thal 2 and α-thaol 1 traits were 12 0% and 4.3%, with the gene frequencies 0.0650 and 0.0217 for -α/ and -/, repectively. The incidence of HB CS trait was 5.8%. with the gene freguency of 0.0292 for α α/ We also found that the incidence of the triplicated ζand triplicated α were 14.7 and 1.0%, with the gene frequencies of 0.0733 and 0.0050 for ζζζ/ and ααα/, respectively The DNA lesion of α-thalassemia in the south is similar to the study of Tanphaichitr et al (1988) in central Thailand. Knowledge of α-globin gene deletion would be useful for prenatal diagnosis of Bart's hydrops to prevent toxemia of pregnancy in the south of Thailand.