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The Lewis antigen system is a human blood group system. It is based upon two genes on chromosome 19 : FUT3 , or Lewis gene; and FUT2 , or Secretor gene. Both genes are expressed in glandular epithelia.
Carbohydrate antigen 19-9 (CA19-9), also known as sialyl-Lewis A, is a tetrasaccharide which is usually attached to O-glycans on the surface of cells. It is known to play a role in cell-to-cell recognition processes. It is also a tumor marker used primarily in the management of pancreatic cancer. [1]
The term human blood group systems is defined by the International Society of Blood Transfusion (ISBT) as systems in the human species where cell-surface antigens—in particular, those on blood cells—are "controlled at a single gene locus or by two or more very closely linked homologous genes with little or no observable recombination between them", [1] and include the common ABO and Rh ...
The i antigen is made of linear repeats, while the structure of the I antigen is branched. [3] Unlike most other blood groups, the two antigens are not encoded by different alleles; rather, I-branching enzyme converts i antigen to I antigen by adding branches. [5] [6] The gene encoding I-branching enzyme is located on chromosome 6. [6]
Because non-secretors cannot form H antigen in body fluids, they cannot express soluble ABO antigens. [1]: 124–6 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 ...
The LW blood system was first described by Landsteiner and Wiener in 1940. [1] It was often confused with the Rh system, not becoming a separate antigen system until 1982. The LW and RhD antigens are genetically independent though they are phenotypically related and the LW antigen is expressed more strongly on RhD positive cells than on RhD negative cells.
Lewis structure, a diagram of a molecule that shows the bonding between the atoms; Lewis acids and bases; Lewis antigen system, a human blood group system; Lewis number, a dimensionless number in fluid dynamics and transport phenomena; Lewis rat, an inbred strain of laboratory rat
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