And that's because the immune system will see antigen A and antigen B as self antigens. So these individuals with blood type AB do not have antibodies for either antigen A or antigen B. Now it is also possible that our individual doesn't have this gene on chromosome nine. And that means if it doesn't have that gene it cannot actually express and produce any one of these antigens. And in such a case if the male parent doesn't have that gene and the female parent doesn't have that gene and they essentially made, they will produce an offspring, an individual in which we basically have neither antigen A nor antigen B on the membrane of that red blood cell. And in that case our immune system will produce both antibodies against antigen A and against antigen B.