For practical purposes, the A B O blood group is sub divided into A. B, AB and O blood groups. Only when problems arise subgroups are looked and distinction of A and B subtypes is made. Subgroups of A B O antigens: There are many subgroups of A B O system. They are mentioned below.
Group A: A1, A2, A3, Ax, Am, Ay, Ael, Aend Group B: B1, B2, B3, Bx, Bm, By, Bel, Bend Only clinically important subgroups are that of A1 and A2 Serological differences between A1and A2 is based on reactivity with human anti-A1 or anti-A1 lectin from Dolichos biflorus. In a blood group, 80% of the population belongs to A1 blood group and about 20% belongs to A2 blood group. About 1-8% of the A2 blood group individuals have anti-A1 antibodies. Also, about 22-35% of the A2B blood group individuals have anti-A1 antibodies. A2 gene has two nucleotides different from that of A1, has diminished enzyme activity and…
