ABO blood group system alleles in white individuals of the ABO gene that produce one's blood type: The same study also identified 18 rare alleles, which generally have a weaker glycosylation activity. People with weak alleles of A can sometimes express anti-A antibodies, though these are usually not clinically significant as they do not stably interact with the antigen at body temperature. Cis AB is another rare variant, in which A and B genes are transmitted together from a single parent. The distribution of the blood groups A, B, O and AB varies across the world according to the population. There are also variations
Blood doping cells into surrounding tissue during each passage through the cardiovascular system. ITPP has been a subject of anti-doping research in both humans and racehorses. Blood transfusions can be traditionally classified as autologous, where the blood donor and transfusion recipient are the same, or as allogeneic/homologous, where the blood is transfused into someone other than the donor. Blood transfusion begins by the withdrawal of 1 to 4 units of blood (1 unit = 450 ml of blood) several weeks before competition. The blood is centrifuged, the plasma components are immediately reinfused, and the corpuscular elements, principally red blood cells (RBCs), are