Fy antigen

The Duffy antigen system is a classification of human blood based on glycoproteins called Fy antigens found on red blood cells and other cells. The primary Duffy antigens are Fy^a and Fy^b, discovered in 1950 and 1951, respectively.1

These antigens function as receptors for chemokines, which are molecules that attract immune cells. Crucially, Duffy antigens also serve as receptors for malarial parasites Plasmodium knowlesi and P. vivax. Individuals with the Fy^a-b- phenotype lack these receptors, providing a degree of protection against malaria. This has led to natural selection favoring this phenotype in populations with high malaria prevalence.1

The Duffy antigens are encoded by the DARC gene, which produces a chemokine receptor protein. Variations in this gene lead to different Duffy phenotypes, with Fy^a+b+ being common in Caucasians and Fy^a-b- being prevalent in people of African descent. Antibodies to Duffy antigens can cause transfusion reactions and hemolytic disease of the newborn.1