Question

What is the rarest blood group?

Answer 1

The presence or absence of certain antigens which trigger an immune response to the foreign particles determines the blood group. There are four major blood groups on the basis of presence and absence of two antigens- A and B on the surface of red blood cells.

Complete answer:
The presence or absence of certain antigens which trigger an immune response to the foreign particles determines the blood group. According to the presence of two antigens- A and B on the surface of red blood cells, the blood group is determined. Alongwith the antigen, there is a protein called Rh factor (also known as Rhesus factor) which can be either present or absent and also determines the blood group.

There are 8 blood groups in total i.e.,
$A^+$
$A^-$
$B^+$
$B^-$
$AB^+$
$AB^-$
$O^+$
$O^-$

For safe blood transfusion, there are some specific ways in which the blood should be matched. Wrong blood transfusion may cause the death of the recipient. People with blood group O are the universal donor because it does not have any antigen on the surface of red blood cells. People with blood group AB are universal recipients because it has both A and B antigen on the surface of red blood cells.

The rarest blood group in the whole world is AB negative. Only around 1% of the total population has an AB negative blood group.

Note: Blood groups are determined by the presence or absence of certain antigens which trigger an immune response to the foreign particles. According to the presence of two antigens- A and B on the surface of red blood cells, the blood group is determined.AB negative blood group is the rarest blood group in the whole world.