ABO / Rhesus blood group system, which most are classified as inside, there are many rare blood type. AB is the rarest of the world's population to less than one percent with the blood type. B & O is also very rare, the world's population each accounting for less than 5%. However, there are 30 recognized beyond the basic two blood typing system, rare blood types, some of which appeared in a handful of people.Blood types in the blood is determined by the presence of certain antigens to create an abundance of. A and B antigens are very common, they make it easy to categorize people by making the antigen, while those with type O blood has neither antigen. Since blood type negative or positive symbol indicates the presence or absence of the Rhesus factor. However, A and B may be present beyond the other antigens, these antigens may react with the blood of some donors. Anyone with a rare blood type to appear, may, for example + A short but he or another antigen, the antigen contained a + donor blood that could cause a bad reaction can be is.
