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.
Human blood group systems three types of cells: The most common type of grouping is the ABO blood group system. The varieties of glycoprotein and glycolipid coating on red blood cells divides blood into four groups: Another antigen, the Rh factor, plays an important part in the grouping of blood. If this is present, the particular blood type is called Rh-positive. If it is absent, it is called Rh-negative. In addition to the ABO and Rh blood group systems, there are more than two hundred minor blood groups that can complicate blood transfusions. These are known as rare blood types. Whereas common blood types