ABO blood group system gives type O. As both "I" and "I" are dominant over "i", only "ii" people have type O blood. Individuals with "II" or "Ii" have type A blood, and individuals with "II" or "Ii" have type B. "II" people have both phenotypes, because A and B express a special dominance relationship: codominance, which means that type A and B parents can have an AB child. A couple with type A and type B can also have a type O child if they are both heterozygous ("Ii","Ii"). The "cis-AB" phenotype has a single enzyme that creates both A and B antigens.
Blood donation the blood that takes the longest to replace. Using this method an individual can donate plasma or platelets much more frequently than they can safely donate whole blood. These can be combined, with a donor giving both plasma and platelets in the same donation. Platelets can also be separated from whole blood, but they must be pooled from multiple donations. From three to ten units of whole blood are required for a therapeutic dose. Plateletpheresis provides at least one full dose from each donation. Plasmapheresis is frequently used to collect source plasma that is used for manufacturing into medications much