Author(s): Wee YC, Tan KL, Chow TW, Yap SF, Tan JA
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Abstract AIM: Interactions between different determinants of alpha-thalassemia raises considerable problems, particularly during pregnancies where antenatal diagnosis is necessary. This study aims to determine the different types of deletional alpha-thalassemia and Hemoglobin Constant Spring (HbCS), and their frequency in Malays, Chinese and Indians in Malaysia. METHODS: DNA from 650 pregnant women from the Antenatal Clinic of the University of Malaya Medical Center in Kuala Lumpur, Malaysia who showed mean cell volume < or =89 fL and/or mean cell hemoglobin < or =28 pg were analyzed for the double alpha-globin gene South-East Asian deletion (--SEA), the -alpha3.7 and -alpha4.2 single alpha-globin gene deletions and HbCS. RESULTS: One hundred and three (15.8\%) of the pregnant women were confirmed as alpha-thalassemia carriers: 25 (3.8\%) were alpha-thalassemia-1 carriers with the --SEA/alphaalpha genotype, 64 (9.8\%) were heterozygous for the -alpha3.7 rightward deletion (-alpha3.7/alphaalpha), four (0.6\%) were heterozygous for the -alpha4.2 leftward deletion (-alpha4.2/alphaalpha), nine (1.4\%) were heterozygous for HbCS (alphaCSalpha/alphaalpha) and one (0.2\%) was compound heterozygous with the -alpha3.7/alphaCSalpha genotype. The double alpha-globin gene --SEA deletion was significantly higher in the Chinese (15\%) compared to the Malays (2.5\%) and not detected in the Indians studied. The -alpha3.7 deletion was distributed equally in the three races. HbCS and -alpha4.2 was observed only in the Malays. CONCLUSION: The data obtained gives a better understanding of the interactions of the different alpha-thalassemia determinants in the different ethnic groups, thus enabling more rapid and specific confirmation of alpha-thalassemia in affected pregnancies where antenatal diagnosis is necessary.
This article was published in J Obstet Gynaecol Res
and referenced in Clinics in Mother and Child Health