# How ABO blood group is determined?

There are several blood groups but important group considered is ABO blood group and Rh factor. Many of us get confused while determining blood group of our child. Here is the simple way how to determine ABO blood group.

If we consider ABO blood group, there are four types namely A, B, AB and O. We all know that AB +ve is considered as Universal recipient and O -ve is considered as Universal donor which means AB +ve can receive blood from any person with any blood group while O -ve can donate blood to any one.

Now we often think that if father is of Blood group A or mother is blood group B, then whether their child can be of blood group o?
Answer is yes, it can be A, B, AB and even O.

So how we can determine this?
There is very simple formula, let us start with Rh factor which signifies positive or negative. A positive means the person is having Rh antigen in blood and either mother or father is positive the offspring will be positive as simple as that.

Determining ABO blood group is a bit complex. As we know chromosomes are in pair, so an antigen can be on both chromosome or on a single one. Now there are two antigens A and B, a person can be of blood group A if both chromosome have A antigen or a single chromosome have A antigen. Same is the case with blood group B. If one chromosome have A antigen and other B then group will be AB and if both chromosome dont have any antigen then blood group O.

Let us consider a case when mother have blood group A and father blood group B or vice versa
Mother chromosome may be C(A) and C(O) or C(A) and C(A).
Father chromosome may be C(B) and C(O) or C(B) and C(B).

If C(A) combines with C(B) of father then Blood group will be AB.
If C(A) combines with C(O) then it will be A, similarly if C(B) combines with C(A) blood group of child will be AB and if C(B) combines with C(O) then blood group B and if C(O) chromosome of both mother and father combines then blood group will be O. Thus if mother and father are of A and B blood group respectively or vice versa child can be any of the four blood group.

If both mother and father have O blood group then child will be of O group only as there is no antigen and of chromosome of both parent will be C(O).

If either father or mother or both is of blood group AB then no child will be of blood group O as the chromosome will be C(A) or C(B).

If you have any other query regarding ABO blood group, you are welcome to ask in our geek forum.