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 monosialylgalactosylgloboside (Type 1 MSGG) in an α1,4 linkage forms the sialyl Lewis A antigen (sLeA), also known as the CA19-9 antigen, the most common tumour marker used primarily in the management of pancreatic and gastrointestinal cancers worldwide (Magnani 2004). If CA19-9 is initially elevated in pancreatic cancer, it may be requested several times during cancer treatment to monitor response and, on a regular basis following treatment, to help detect recurrence of the cancer.