Duffy antigen system

Duffy Antigen System

The Duffy antigen system (also known as Fy or the Duffy blood group system) is a collection of antigens on red blood cells that are of significant importance in medicine, particularly in transfusion medicine and the study of malaria. The system was first identified in the 1950s and is named after the patient in whom the antigen was first discovered. The Duffy antigen system is encoded by the FY gene (also known as DARC, for Duffy Antigen/Receptor for Chemokines) and is located on chromosome 1. This gene determines the presence of the Duffy antigens on the surface of red blood cells.

Genetics

The FY gene exhibits three main alleles: FY*A, FY*B, and FY*O. The FY*A and FY*B alleles encode for the Fya and Fyb antigens, respectively, and differ by a single nucleotide polymorphism. The FY*O allele, prevalent in individuals of African descent, does not produce a functional Duffy antigen due to a mutation that prevents the expression of the Duffy protein on red blood cells. Individuals homozygous for the FY*O allele are resistant to infection by Plasmodium vivax, one of the parasites that cause malaria, as the Duffy antigen acts as a receptor for this parasite.

Clinical Significance

1. 1. 1. Transfusion Medicine

In transfusion medicine, the Duffy antigen system is crucial for matching blood transfusions to avoid hemolytic reactions. Individuals who lack the Duffy antigen (Fy(a-b-)) can develop antibodies against the Duffy antigens if exposed through transfusion or pregnancy, leading to potential hemolytic transfusion reactions or hemolytic disease of the newborn.

1. 1. 1. Malaria

The Duffy antigen is a known receptor for the Plasmodium vivax malaria parasite. The absence of the Duffy antigen in individuals with the FY*O allele provides natural resistance to P. vivax malaria, a phenomenon that has significant implications for malaria control and treatment strategies in regions where this allele is common.

Epidemiology

The distribution of Duffy antigens varies significantly among different populations. The FY*O allele is highly prevalent in sub-Saharan Africa, providing a protective effect against P. vivax malaria. In contrast, the Fya and Fyb antigens are more common in European and Asian populations.

Clinical Applications

Understanding the Duffy antigen system has applications in transfusion medicine, malaria research, and understanding human migration and evolution. The development of drugs targeting the Duffy antigen pathway for malaria treatment and the use of Duffy antigen typing in blood transfusion practices are areas of ongoing research.

See Also

• Blood transfusion
• Malaria
• Red blood cell antigens
• Genetic resistance to malaria