The H antigen is formed with the addition of a fucose (Fuc) sugar onto one of two precursor oligosaccharide sequences, Type 1 (RBCs) or Type 2 (secreted) chains. The FUT1 gene (aka H gene) found in hematopoietic cells produces galactoside 2-α-L-fucosyltransferase 1 (FUT1 aka α-1,2-fucosyltransferase 1) which mediates the transfer of a fucose (Fuc) sugar to the galactose (Gal) sugar of the Type 2 chain precursor Gal-β1,4-GlcNAc-β1,3-Gal-R (where R is a glycosphingolipid) to form the H antigen (Larsen et al. 1990). This is an essential step for subsequent formation of A and B antigens. Mutations that inactivate the FUT1 gene can result in the 'Bombay phenotype' where no A, B or H antigens are produced on RBCs (Koda et al 1997, Kaneko et al. 1997).
Larsen, RD, Ernst, LK, Nair, RP, Lowe, JB
Kaneko, M, Nishihara, S, Shinya, N, Kudo, T, Iwasaki, H, Seno, T, Okubo, Y, Narimatsu, H
Koda, Y, Soejima, M, Johnson, PH, Smart, E, Kimura, H
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