Heterogeneity in alpha-thalassemia interactions in Malays, Chinese and Indians in Malaysia.
OBJECTIVE
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.


CONCLUSIONS
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.
Wee
Yong-Chui
YC
Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. weeyongchui@yahoo.com
Tan
Kim-Lian
KL
Chow
Teresa Wai-Ping
TW
Yap
Sook-Fan
SF
Tan
Jin-Ai Mary Anne
JA
D000293:Adolescent; D000328:Adult; D044466:Asian People / Q000235:genetics*; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D005260:Female; D006580:Genetic Carrier Screening; D005914:Globins / Q000235:genetics; D006801:Humans; D008296:Malaysia; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000175:diagnosis / Q000235:genetics*; D017085:alpha-Thalassemia / Q000150:complications* / Q000175:diagnosis / Q000235:genetics* / Q000517:prevention & control
D005914:Globins; D004247:DNA