A Wiki about biochemical individuality


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Blood group antigen proteins (chart)


The Colton antigen system (Co) is present on the membranes of red blood cells and in the tubules of the kidney (1) and helps determine a person's blood type. The Co antigen is found on a protein called aquaporin-1 which is responsible for water homeostasis and urine concentration. (2)


The Co antigen is important in transfusion medicine. 99.8% of people possess the Co(a) allele. Individuals with Co(b) allele or who are missing the Colton antigen are at risk for a transfusion reaction such as hemolytic anemia or alloimmunization. Antibodies against the Colton antigen may also cause hemolytic disease of the newborn, in which a pregnant woman's body creates antibodies against the blood of her fetus, leading to destruction of the fetal blood cells. (3)


  • 110450: OMIM entry for the Colton antigen



1. Denker BM, Smith BL, Kuhajda FP, Agre P. Identification, purification, and partial characterization of a novel Mr 28,000 integral membrane protein from erythrocytes and renal tubules. J Biol Chem 1988;263:15634-15642. PMID 3049610

2. King LS, Choi M, Fernandez PC, Cartron JP, Agre P.Defective urinary-concentrating ability due to a complete deficiency of aquaporin-1. N Engl J Med. 2001 Jul 19;345(3):175-9. PMID 11463012

3. Covin RB, Evans KS, Olshock R, Thompson HW. Acute hemolytic transfusion reaction caused by anti-Coa. Immunohematol. 2001 Jun;17(2):45-9. PMID 15373591