FUT2

Galactoside 2-alpha-L-fucosyltransferase 2 is an enzyme that in humans is encoded by the FUT2 (fucosyltransferase 2) gene. FUT2 is a key enzyme that catalyzes the transfer of L-fucose from guanosine diphosphate-beta-L-fucose to the terminal galactose on both O- and N-linked glycans of cell surface glycoproteins and glycolipids. This enzymatic activity is essential for the synthesis of the H antigen, a precursor required for the formation of ABO blood group antigens, and determines "secretor status"—the presence of blood group antigens in bodily fluids such as saliva. Beyond its role in blood group antigen synthesis, FUT2 influences cell-cell interactions, modulates the composition of the gut microbiome, and impacts susceptibility to infections and autoimmune diseases, highlighting its broad significance in human health and disease. Approximately 20% of Caucasians are non-secretors due to the G428A (rs601338) and C571T (rs492602?) nonsense mutations in FUT2 and therefore have strong although not absolute protection from the norovirus GII.4.