Molecular basis for Lewis alpha(1,3/1,4)-fucosyltransferase gene deficiency (FUT3) found in Lewis-negative Indonesian pedigrees.

The Le(a) and Le(b) human blood group antigens are synthesized in tissues producing exocrine secretions; they also circulate in plasma, where they are adsorbed by erythrocytes. They are synthesized by two fucosyltransferases, encoded by Lewis (FUT3) and secretor (FUT2) loci. This genetic model has been challenged because some erythrocyte Lewis-negative individuals express Lewis antigens in saliva.

Assignment of 112 microsatellite markers to 23 chromosome 11 subregions delineated by somatic hybrids: comparison with the genetic map.

Using a panel of 25 somatic cell hybrids, we have regionally localized 112 microsatellite markers generated by Généthon and assigned to chromosome 11. A genetic map of 74 of them was produced using linkage analysis of the eight largest CEPH (Centre d'Etude du Polymorphisme Humain) families. They could be ordered on chromosome 11 with an average distance of 2.

Molecular basis for plasma alpha(1,3)-fucosyltransferase gene deficiency (FUT6).

While most humans express an alpha(1,3)-fucosyltransferase in plasma, 9% of individuals on the isle of Java (Indonesia) do not express this enzyme. Ninety-five percent of these plasma alpha(1,3)-fucosyltransferase-deficient individuals have Lewis negative phenotype on red cells, suggesting strong linkage disequilibrium between these two traits. To define the molecular basis for this plasma deficiency and to determine which of two candidate human alpha(1,3)-fucosyltransferase genes encode this enzyme (FUT5 and FUT6), we cloned and analyzed alleles at these two loci from an Indonesian individual deficient in plasma alpha(1,3)-fucosyltransferase activity.

The gene encoding myeloid alpha-3-fucosyl-transferase (FUT4) is located between D1 1S388 and D11S919 on 11q21.

The last step in the biosynthesis of Le(x) antigen, the addition of a fucose to precursor polysaccharides, can be catalyzed by different alpha-3-fucosyltransferases. We localized the gene (FUT4) encoding myeloid alpha-3-fucosyltransferase by PCR assay using panels of somatic cell and radiation hybrids which retain different rearrangements of chromosome 11. FUT4 was assigned to chromosome band 11q21 between D11S388 and D11S919.

Molecular genetics of alpha-L-fucosyltransferase genes (H, Se, Le, FUT4, FUT5 and FUT6).

Six human alpha-L-fucosyltransferase genes have been registered in the GDB as FUT1 to FUT6 according to the chronology of their description. FUT1 and FUT2 encode the alpha(1,2)fucosyltransferases H and Se respectively. The FUT2 gene has not been cloned, but it is expected to be closely linked to FUT1 on the long arm of chromosome 19.