Molecular genetics of H, Se, Lewis and other fucosyltransferase genes.

Seven human fucosyltransferase genes have been cloned and registered in the Genome Data Base (GDB) as FUT1 to FUT7. According to their acceptor specificity, two main groups of enzymes can be distinguished. The alpha-2-fucosyltransferases: FUT1 (H) of red cells and vascular endothelium and FUT2 (Se) of exocrine secretions. The alpha-3-fucosyltransferases: FUT3 (Lewis) of exocrine secretions; FUT4 (myeloid) of white cells and brain; FUT5 whose tissue distribution has not been defined as yet; FUT6 (plasma) present in plasma, renal proximal tubules and hepatocytes; FUT7 (leukocyte) found in neutrophils. A high DNA sequence homology has been detected among the genes within each of these two groups, while no homology has been detected between the genes of the two groups. Point mutations responsible of inactivating genetic polymorphisms have been found for FUT1, FUT2, FUT3 and FUT6, while FUT4 and FUT7 seem to be genetically monomorphic. FUT4 has been detected in all tissues of 5 to 10 weeks old human embryos suggesting that it may play a role in development. FUT7 is a candidate for the control of the synthesis of the receptors of selectin mediated cell adhesion.