Sub divisions of the Blood group -A
Depending upon the difference In the degree of behavior, the blood group ‘A’ has been separated into A1, A2 A3 and A4 subgroups. Comparatively A1 is more common and the occurrence and reactivity of A2,
A3 and A4 gradually decreases. Each of the A’ sub groups are determined by a separate gene and all these genes are alleles. The genes A2 A3 and A4 normally occur in combination with A1 as A2 A1 A3 A1 and A4 A1. A is dominant to A2, A3 and A4. Like wise A1 is dominant over A2 and A4 and so on. Homozygous A1A1 are very common whereas homozygous A2 A2 or A2A3 are Very rare.
The ‘oasis of sub divisions of ‘A’ blood group is its reaction with B- serum which contain two types of antibodies a and a,. The corpuscles of blood group B, react and remove both the antibodies a, and a, The corpuscles of A, group combine only with a antibodies while leaving, a, antibodies In the B - serum.
- In a person of blood group AS, there might be A1 A2 A3 or A4 Hence AB blood group can be divided into sub groups A 1B, A2 B, A3 B, and A4 B. There is some evidence that the B’ group is also divided into sub groups but It has not been established so far.
Knowledge of A B 0 blood groups is very much helpful in solving cases of disputed parentage and settles the cases of illegitimacy.
Although cases of mix up parentage are rare in hospitals, but these may happen in rare cases. In the past, two sets of parents had taken babies home from a particular hospital at the same time. Both the families discovered it. But the family 2 is not read9 for the exchange. Blood tests in that case demonstrated the possibility of exchange and the exchange finally satisfied both the families.
Blood tests can be used to solve the cases of claimants to estates or in certain kinds of criminal proceedings.