Colton antigen system

Colton antigen system is a blood group system associated with the Aquaporin-1 (AQP1) protein, which is a water channel protein found in the red blood cell membrane. The Colton antigen system is named after the patient in whom the first antibody was identified.

History[edit | edit source]

The Colton antigen system was first described in 1953 by Landsteiner and Levine, who discovered an antibody in the serum of a patient named Colton. This antibody was found to react with all red blood cells except those of the patient and his family, leading to the identification of a new blood group system.

Genetics[edit | edit source]

The Colton antigen system is encoded by the AQP1 gene located on chromosome 7. This gene encodes the Aquaporin-1 protein, which forms a water channel in the red blood cell membrane. There are three known alleles in the Colton system: Co(a), Co(b), and Co3. The Co(a) and Co(b) antigens are determined by a single amino acid substitution at position 45 of the AQP1 protein.

Clinical significance[edit | edit source]

The Colton antigen system is clinically significant in blood transfusion and pregnancy. Antibodies to the Colton antigens can cause hemolytic transfusion reaction and hemolytic disease of the fetus and newborn (HDFN). However, these reactions are rare because anti-Co(a) and anti-Co(b) are usually not clinically significant, and the Co3 antigen is high frequency, meaning it is present in most individuals.