The FUT3 gene (originally named the Le gene) expresses galactoside 3(4)-L-fucosyltransferase present on the Golgi membrane. FUT3 catalyses the α1,4 and α1,3 addition of fucose to Type 1 and Type 2 oligosaccharide chains respectively, thereby playing a role in Lewis blood group determination (Kukowska-Latallo et al. 1990). Here, the addition of fucose to the subterminal N-acetylglucosaminyl (GlcNAc) residue of Type 1 chains in an α1,4 linkage forms the Lewis A antigen (LeA). In Lewis negative (Le(a- b-)) individuals, FUT3 is inactivated by either of two mutations resulting in a single amino acid substitution in the catalytic region (Nishihara et al. 1993). LeA is found on red blood cells (~20%) and in saliva and other secretions (>90%) of Europeans. LeA is a water-soluble antigen and red blood cells acquire Lewis specificity by adsorbing it onto their surfaces from blood plasma.