Lewis antigen system

The Lewis antigen system is a human blood group system based upon genes on chromosome 19 q13.3, (FUT2) and 19p13.3 (FUT3), which both have fucosyltransferase activity. There are two main types of Lewis antigens, Lewis a and Lewis b. They are red cell antigens which are not produced by the erythrocyte itself. Instead, Lewis antigens are a component of exocrine epithelial secretions, and are subsequently adsorbed onto the surface of the erythrocyte.

It is possible to have any combination of Lewis a, Lewis b, both or neither antigens. The most common are Lewis a negative and Lewis b positive (Le a-, Le b+). Having both antigens is extremely rare.

The link between the Lewis blood group and secretion of the ABO blood group antigens was possibly the first example of multiple effects of a human gene.^[1] The presence of fucosyltransferase converts the Lewis a antigen to Lewis b. People with Lewis a antigens are usually ABH non-secretors, and the presence of the Lewis b antigen makes a person a secretor. Lewis negative (Le a-, Le b-) can be either secretors or non-secretors.

References

External links

• Lewis at BGMUT Blood Group Antigen Gene Mutation Database at NCBI, NIH