responsible for linking fucose in a α1-2 linkage to elongate the HMO chain.
The enzyme FUT3 is encoded for by the Lewis blood group gene;
this enzymecatalyses the reaction between fucose in a α1-3/4 linkage,
creating further fucosylated oligosaccharides.
As a result of the different expressions of these enzymes,
there are four main phenotypes in relation to HMO profile: