Molecular analysis of secretor type alpha(1,2)-fucosyltransferase gene mutations in the Chinese and Thai populations.

BACKGROUND: The human Lewis histo-blood group system belongs to a family of structurally related oligosaccharides. The mutations of fucosyltransferase genes alpha(1,2)-fucosyltransferase (FUT2 or Se) and alpha(1,3/1,4)-fucosyltransferase (FUT3 or Le), are responsible for the polymorphism of Lewis blood group phenotypes. However, a population study of the FUT2 mutation in Chinese and Thais has not yet been done, and there is some controversy about the phenotypes of Le(a+b+) and Le(a+b-). STUDY DESIGN AND METHODS: One hundred twentyfour Chinese and 70 Thais were phenotyped for Lea and Le(b). DNA samples were studied by polymerase chain reaction and then by a restriction enzyme digestion method to distinguish wild-type and six known mutations. Direct sequencing was done for controls and some uncertain cases.
RESULTS: A new mutation, C302T mutation, was found in 2 of 136 chromosomes in the Thai population; none were discovered in Chinese. The frequencies of the normal and six mutant alleles among Chinese and Thais, respectively, were as follows: 134 (54.0%) of 248 and 58 (41.4%) of 140 were wild-type (Se); 0 of 248 and 2 of 140 (both 1.4%) had the G428A mutation; 120 (48.4%) of 248 and 75 (53.6%) of 140 had the A385T mutation; 2 (0.81%) of 248 and 0 of 140 had the C571T mutation; and 1 (0.4%) of 248 and 3 (2.2%) of 140 had the G849A mutation. Only 1 Chinese (0.4%) of 248 had the C628T mutation, and none had fusion gene mutation.
CONCLUSION: The FUT2 genes encoding for the phenotypes Le(a+b+) and Le(a+b-) are the same. The function and character of the mutant enzyme may play an important role in the phenotype. The methods used in this study are clinically applicable in population studies of the FUT2 gene polymorphism to explore relationships among different ethnic groups and correlations between phenotype and genotype.