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Duffy antigen system
Duffy antigen/chemokine receptor (DARC), also known as Fy glycoprotein (FY) or CD234 (Cluster of Differentiation 234), is a protein that in humans is encoded by the ACKR1 gene.
The Duffy antigen is located on the surface of red blood cells, and is named after the patient in whom it was discovered. The protein encoded by this gene is a glycosylated membrane protein and a non-specific receptor for several chemokines. The protein is also the receptor for the human malarial parasites Plasmodium vivax, Plasmodium knowlesi and simian malarial parasite Plasmodium cynomolgi. Polymorphisms in this gene are the basis of the Duffy blood group system.
It was noted in the 1920s that black Africans had some intrinsic resistance to malaria, but the basis for this remained unknown. The Duffy antigen gene was the fourth gene associated with the resistance after the genes responsible for sickle cell anaemia, thalassemia and glucose-6-phosphate dehydrogenase.[citation needed]
In 1950, the Duffy antigen was discovered in a multiply-transfused hemophiliac named Richard Duffy, whose serum contained the first example of anti-Fya antibody. In 1951, the antibody to a second antigen, Fyb, was discovered in serum. Using these two antibodies, three common phenotypes were defined: Fy(a+b+), Fy(a+b-), and Fy(a-b+).[citation needed]
Several other types were later discovered bringing the current total up to 6: Fya, Fyb, Fy3, Fy4, Fy5 and Fy6. Only Fya, Fyb and Fy3 are considered clinically important. Reactions to Fy5 have also rarely been reported. The Fy4 antigen, originally described on Fy (a–b–) RBCs, is now thought to be a distinct, unrelated antigen and is no longer included in the FY system.[citation needed]
The Duffy antigen/chemokine receptor gene (gp-Fy; CD234) is located on the long arm of chromosome 1 (1.q22-1.q23) and was cloned in 1993. The gene was first localised to chromosome 1 in 1968, and was the first blood system antigen to be localised. It is a single copy gene spanning over 1500 bases and is in two exons. The gene encodes a 336 amino acid acidic glycoprotein. It carries the antigenic determinants of the Duffy blood group system which consist of four codominant alleles—FY*A and FY*B—coding for the Fy-a and Fy-b antigens respectively, FY*X and FY*Fy, five phenotypes (Fy-a, Fy-b, Fy-o, Fy-x and Fy-y) and five antigens. Fy-x is a form of Fy-b where the Fy-b gene is poorly expressed. Fy-x is also known as Fy-bweak or Fy-bWk.
This gene has been redesignated ACKR1.
Fy-a and Fy-b differ by in a single amino acid at position 42: glycine in Fy-a and aspartic acid in Fy-b (guanine in Fy-a and adenosine in Fy-b at position 125). A second mutation causing a Duffy negative phenotype is known: the responsible mutation is G -> A at position 298. The genetic basis for the Fy(a-b-) phenotype is a point mutation in the erythroid specific promoter (a T -> C mutation at position -33 in the GATA box). This mutation occurs in the Fy-b allele and has been designated Fy-bEs (erythroid silent). Two isotypes have been identified. The Fy-x allele is characterized by a weak anti-Fy-b reaction and appears to be the result of two separate transitions: Cytosine265Threonine (Arginine89Cysteine) and Guanine298Adenosine (Alanine100Threonine). A third mutation (a transversion) in this gene has also been described - G145T (Alanine49Serine) - that has been associated with the Fy-x phenotype.
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Duffy antigen system AI simulator
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Duffy antigen system
Duffy antigen/chemokine receptor (DARC), also known as Fy glycoprotein (FY) or CD234 (Cluster of Differentiation 234), is a protein that in humans is encoded by the ACKR1 gene.
The Duffy antigen is located on the surface of red blood cells, and is named after the patient in whom it was discovered. The protein encoded by this gene is a glycosylated membrane protein and a non-specific receptor for several chemokines. The protein is also the receptor for the human malarial parasites Plasmodium vivax, Plasmodium knowlesi and simian malarial parasite Plasmodium cynomolgi. Polymorphisms in this gene are the basis of the Duffy blood group system.
It was noted in the 1920s that black Africans had some intrinsic resistance to malaria, but the basis for this remained unknown. The Duffy antigen gene was the fourth gene associated with the resistance after the genes responsible for sickle cell anaemia, thalassemia and glucose-6-phosphate dehydrogenase.[citation needed]
In 1950, the Duffy antigen was discovered in a multiply-transfused hemophiliac named Richard Duffy, whose serum contained the first example of anti-Fya antibody. In 1951, the antibody to a second antigen, Fyb, was discovered in serum. Using these two antibodies, three common phenotypes were defined: Fy(a+b+), Fy(a+b-), and Fy(a-b+).[citation needed]
Several other types were later discovered bringing the current total up to 6: Fya, Fyb, Fy3, Fy4, Fy5 and Fy6. Only Fya, Fyb and Fy3 are considered clinically important. Reactions to Fy5 have also rarely been reported. The Fy4 antigen, originally described on Fy (a–b–) RBCs, is now thought to be a distinct, unrelated antigen and is no longer included in the FY system.[citation needed]
The Duffy antigen/chemokine receptor gene (gp-Fy; CD234) is located on the long arm of chromosome 1 (1.q22-1.q23) and was cloned in 1993. The gene was first localised to chromosome 1 in 1968, and was the first blood system antigen to be localised. It is a single copy gene spanning over 1500 bases and is in two exons. The gene encodes a 336 amino acid acidic glycoprotein. It carries the antigenic determinants of the Duffy blood group system which consist of four codominant alleles—FY*A and FY*B—coding for the Fy-a and Fy-b antigens respectively, FY*X and FY*Fy, five phenotypes (Fy-a, Fy-b, Fy-o, Fy-x and Fy-y) and five antigens. Fy-x is a form of Fy-b where the Fy-b gene is poorly expressed. Fy-x is also known as Fy-bweak or Fy-bWk.
This gene has been redesignated ACKR1.
Fy-a and Fy-b differ by in a single amino acid at position 42: glycine in Fy-a and aspartic acid in Fy-b (guanine in Fy-a and adenosine in Fy-b at position 125). A second mutation causing a Duffy negative phenotype is known: the responsible mutation is G -> A at position 298. The genetic basis for the Fy(a-b-) phenotype is a point mutation in the erythroid specific promoter (a T -> C mutation at position -33 in the GATA box). This mutation occurs in the Fy-b allele and has been designated Fy-bEs (erythroid silent). Two isotypes have been identified. The Fy-x allele is characterized by a weak anti-Fy-b reaction and appears to be the result of two separate transitions: Cytosine265Threonine (Arginine89Cysteine) and Guanine298Adenosine (Alanine100Threonine). A third mutation (a transversion) in this gene has also been described - G145T (Alanine49Serine) - that has been associated with the Fy-x phenotype.