The Relationship betweenLewis/SecretorGenotypes and Serum Carbohydrate Antigen 19-9 Levels in a Korean Population

The Lewis histo-blood group system consists of 2 major antigens-Lea and Leb-and a sialyl Lewis antigen-carbohydrate antigen (CA) 19-9. We investigated the distribution of Lewis genotypes and evaluated the relationship between the Lewis/Secretor genotypes and the serum level of CA 19-9 in a Korean population to identify whether the serum CA 19-9 levels are influenced by the Lewis/Secretor genotypes.The study included 242 individuals who had no malignancies. Lewis genotyping was performed for the 59TG, 508GA and 1067TA polymorphic sites. The Secretor genotype was determined through analysis of the 357CT and 385AT polymorphic sites and the fusion gene. Serum CA 19-9 level was analyzed using an electrochemiluminescence immunoassay.Individuals carrying the 3 common genotypes-Le/Le, Le/le(59,508), and Le/le(59,1067)-accounted for 95% of the study population. In the Korean population, the allelic frequencies of Le, Le(59), le(59,508), and le(59,1067) were 0.731, 0.010, 0.223, and 0.035, respectively. We found a significant difference in serum CA 19-9 concentrations among the 9 Lewis/Secretor genotype groups (P0.001). The serum CA 19-9 levels in subjects with genotype groups 1 and 2 (Le/- and se/se) were higher than those with genotype groups 3-6 (Le/- and Se/-; 15.63 vs 6.64 kU/L, P0.001).Le/Le, Le/le(59,508), and Le/le(59,1067) are frequent Lewis genotypes in Koreans. Because serum CA 19-9 levels are significantly influenced by the Lewis/Secretor genotypes, caution is suggested when interpreting the serum CA 19-9 levels.