However, there are six other blood types that are still present in the population. In the U.S., O positive is the most common, while AB negative is the rarest. The odds of this particular combination are simply lower than any other combination. The allele frequency for type O is higher, while the frequency for A and B is significantly lower. To produce AB blood, an individual must inherit an A allele and a B allele, not an O allele.
There are few combinations of alleles which can produce it, and the alleles are relatively rare. Approximately 0.6 percent of the population is AB Negative (the rarest blood type), and 3.4 percent is AB Positive, which are potential universal plasma donors, although it's the most rare blood type.ĪB plasma is universal, and can be used for all patients regardless of their blood type.ĪB-negative is the rarest because it is only present in 1 out of 167 individuals. People with AB blood inherited an A gene from one parent and a B gene from the other. Therefore, the likelihood of an ii pairing is higher than that of the Ai pairing, making O the most common blood type. In other words, there are many more i alleles in the gene pool, so the chances of getting ii are higher than AA or Ai. The i allele is much more common than A, which is much more common than B. This means a person expressing AA or Ai will have type A blood group BB or Bi will be of type B blood group AB will be of type AB blood group and ii will be of the type O blood group. It’s important to remember alleles (different versions of a gene that determine specific traits) do not appear with equal frequency in the gene pool. So, in order to be type O, we need both parents to be O.Ī recent study published in the journal Nature Medicine evaluated how a single blood test could help detect as many as 11 indicators of deteriorating health. The gene for type O is recessive, because we need to have one gene for O and one for A then we still end up with A antigens on our cell membranes. This means we only need one ABO gene that is type A for us to express type A blood we only need one copy to be type B to express type B blood but we need two copies of the O trait to have O type blood. Traits A and B are dominant, and O is recessive. When it comes to the ABO gene, there are three possible traits, including: A, B, or O. Dominant means we only need one copy for the trait to express recessive means we need both copies to express that trait.
Typically, every gene (with the exception of the Y Chromosome) comes in pairs, meaning we get two copies of every possible trait. So why is type O positive the most common?įirst, we need to understand clearly what 'dominant and recessive trait' means. Meanwhile, the universal red cell donor has type O negative blood type. Blood types vary by ethnic group, with more Hispanic people possessing O blood type, while Asian people are more likely to be type B. O positive is the most common blood type present in 37 percent of the U.S. Type O Positive: The Most Common Blood Type And Why This mean RH negative blood is given to RH-negative patients, and either Rh positive blood, or Rh negative blood may be given to Rh positive patients. There are four major blood groups determined by the presence or absence of two antigens - A and B on the surface of red blood cells: Group A has only A antigen on red cells (and B antibody in the plasma) Group B has only the B antigen on red cells (and A antibody in the plasma) Group AB has both A and B antigens on red cells (but neither A nor B antibody in the plasma) and Group O has neither A nor B antigens on red cells (but both A and B antibodies in the plasma.) Aside from A and B antigens, there is a third antigen called the Rh factor, which indicates either present (+) or absent (-). Some antigens can trigger our immune system to attack transfused blood, which is why transfusions are based on careful blood typing and crossmatching. Blood types are determined by the presence or absence of certain antigens - substances that can trigger an immune response if they are foreign to the body, according to the American Red Cross. However, lingering questions remain, such as: why are some blood types more common than others? ABO Blood Systemīlood is made of the same basic elements (red blood cells, white blood cells, platelets, and plasma), but not all blood is alike. We feel a sense of pride with our biological distinction, but don't know what it means to be type _, aside from knowing what type of blood we can receive in transfusions. Many of us know our blood type from our parents, or after donating blood for the first time.