Modification of branched N-glycans structures such as bisecting GlcNAc, β-1,6-GlcNAc and core fucose (α-1,6-fucose), the enzymatic products of MGAT3 and FUT6 genes, shown to be abnormal in galactosaemia [9], are highly associated with biological functions involving cell adhesion [34, 36]. The gene discussed is MGAT3; the disease is galactosemia.