The Lewis blood group system is a complex genetic blood group system that classifies individuals into distinct phenotypes based on the presence or absence of certain antigens on red blood cells and in body fluids. It was discovered by Bernard Lewis in 1946 and is named after him.
The Lewis system is composed of several antigens, primarily the Lea and Leb antigens. These antigens are determined by specific genes that are inherited in an autosomal recessive manner. The presence of the Lea antigen is determined by the FUT3 gene, while Leb antigen expression is dependent on the interaction between FUT2 and FUT3 genes.
The Lewis blood group system has three main phenotypes: Le(a-b+), Le(a+b-), and Le(a-b-). Individuals who are Le(a-b+) possess the Lea antigen but lack the Leb antigen. On the other hand, those who are Le(a+b-) have the Leb antigen but lack the Lea antigen. Lastly, individuals who do not express either antigen are classified as Le(a-b-).
This blood group system is significant in transfusion medicine as the presence of Lewis antigens can influence compatibility between blood donors and recipients. Additionally, the Lewis system has been associated with various diseases, such as gastric cancer, ulcers, and infections.
To determine an individual's Lewis blood group phenotype, various serologic and molecular methods can be employed, including antibody testing, red blood cell agglutination assays, and DNA sequencing.
