Search

Conclusions: This update of the H blood group system (Scharberg EA, Olsen C, Bugert P. The H blood group system. Immunohematology 2016;32:112-8) reports 11 new FUT1 null alleles: 8 causative for the H- phenotype (Bombay phenotype, Oh), 3 in para-Bombay cases, and 5 new FUT1 alleles causative for a weak H phenotype (para-Bombay, H+w). The H blood group system (International Society of Blood Transfusion system 18) consists of a single antigen (H) defined by a terminal fucose residue found on red blood cells (RBCs) and in secretions. The H antigen is synthesized on the RBC surface by the FUT1 gene product fucosyltransferase 1. On epithelial cells and in body fluids, the H antigen is synthesized by the FUT2 gene product fucosyltransferase 2.

The H blood group system, ISBT symbol H (018), consists of a single antigen (H) defined by a terminal fucose residue found on red blood cells and in secretions formed by the action of α-1,2-fucosyltransferases 1 (α2FucT1) and 2 (α2FucT2), respectively. Mutant alleles of the corresponding FUT1 and FUT2 genes result in either a H– phenotype (Bombay phenotype, Oh) or a weak H phenotype (para-Bombay, H+w). In addition, the FUT2 gene is the molecular basis of the secretor (Se) status, and homozygosity or compound heterozygosity for null alleles is associated with the nonsecretor (se) status. H– individuals have natural anti-H (mostly IgM), which can cause severe hemolytic transfusion reactions with intravascular hemolysis.