Distribution of and polymorphisms and corresponding CA19-9 antigen expression in a Chinese population.

The () and () genes, corresponding to secretion of Lewis ABO (H) histo-blood group antigen CA19-9, are highly polymorphic with differences between populations. In this study, the and genes in 316 Chinese participants were sequenced to detect polymorphisms, and the associated CA19-9 antigen secretion was also measured. In total, 14 genotypes of and 10 genotypes of were verified. /, / and / were the main genotypes of with frequencies of 53.2%, 10.7% and 3.5%, respectively. /, / and / were the main genotypes of , with frequencies of 21.4%, 18.6% and 16.2%, respectively. The alleles and were found extensively in the Chinese population, and the frequency of allele was shown to be higher than previously reported. Phenotype analysis revealed that 9.8% of individuals were the Lewis-negative type and 22.5% were the secretor-negative type. Combined phenotypes showed that 3.2% of participants were of 'double-negative' phenotype (le, se) and 19.3% were of single dominant non-secretor phenotype (Le, se). Serum Lewis antigen CA19-9 levels were significantly different between subgroups and consistent with the defined phenotype. Our study revealed the unique distribution of and polymorphisms in a large Chinese population, and decoded the combined genotypes of the two CA19-9-related genes.