Lewis Blood Group Antigens

**Definition:** Carbohydrate antigens structurally related to the ABH BLOOD-GROUP SYSTEM. They may occur as a modification of saccharide chains on glycolipids or glycoproteins on cell surfaces or in plasma, or as free oligosaccharides in secretions. Lewis antigens are not synthesized in blood cells. Instead Lewis glycolipids present in plasma are absorbed onto the surface of ERYTHROCYTES; LYMPHOCYTES; and PLATELETS. The phenotypes Le(a) and Le(b) are the result of the actions of two genes the Le gene (fucosyltransferase FUT3) and the Se gene (fucosyltransferase FUT2) on the precursor carbohydrate, glycolipid or glycoprotein. Other FUCOSYLTRANSFERASES can also synthesize the Lewis antigens.

**Tree numbers:** - D23.050.301.290.544 - D23.050.705.230.544

**Synonyms:** - Le(a) Blood Group System - Lewis Blood-Group System - Lewis System