The expression of ABO blood group antigens is determined by the interaction of three genes: the ABO gene, which controls expression of the A and B antigens; the FUT1 or H gene, which controls expression of the H antigen, the precursor of ABO antigens; and the<unk>  gene, FUT2 or Se. All of these genes encode glycosyltransferases, which are enzymes that add sugars to precursor substances to create new substances. The H antigen is required for ABO blood group antigens to be formed. The Se gene, which encodes the enzyme α-2-L-fucosyltransferase, controls the formation of H antigen in bodily secretions. In people with the<unk>  genotype, the enzyme converts a precursor substance found in body fluids to the H antigen, which is then modified by the glycosyltransferases encoded by the ABO gene to produce the antigens corresponding to the person's ABO blood type. Because non-secretors cannot form H antigen in body fluids, they cannot express soluble ABO antigens. Lewis blood group phenotypes are controlled by the FUT3 or Le gene and the Se gene. There are two major antigens in the Lewis system: Le(a) and Le(b). Individuals who are negative for Le express neither antigen and their blood type is designated as Le(a-b-). In individuals who are positive for Le, the blood type is determined by the person's<unk> . The Le gene encodes a glycosyltransferase that produces the Le(a) antigen from a precursor substance. In<unk> s, α-2-L-fucosyltransferase modifies this precursor substance, which causes it to form Le(b) when acted on by the enzyme encoded by the Le gene. Thus,<unk> s who are positive for Le express the Le(a-b+) type, while non-secretors who are positive for Le express the Le(a+b-) blood type.
Secretor status
Blood type
History of pathology
SAMPLE history
Indian blood group system
Junior blood group system
Hh blood group
Lan blood group system