Fy(a) antigen

The Fy(a) antigen belongs to the Duffy antigen system. This antigen is a glycoprotein that is expressed on the red cells, as well as other tissues, including brain, kidney, spleen, heart, and lung. Anti-Fy(a) antibodies are common and are usually formed in response to transfusion or pregnancy. Anti-Fy(a) can cause acute or delayed transfusion reactions or hemolytic disease of the fetus and newborn (HDFN).