Explain the genetic basis of ABO blood grouping man.

Explanation

The inheritance of different blood groups ABO was discovered by Benstein in 1925. These blood groups are govermed by a number of multiple allelic series . The determination of blood group of any person is decided by the three autosomal ll alleles present on the chromosome 9. the gene I. . the gene I exists in three allelic forms namely `I^(A) ,I^(B) ` and `I^(@) I^(A)` represents A antigen `I^(B)` denotes B antigen `I^(o)` allele specifies no antigen.
From the crosses of different combination it is evident that `I^(A)` and `I^(B)` are dominant over `I^(O)` gene , but codominant to each other `(I^(A)= I^(B))` then their dominance hierarchy can be given as `I^(A) = I^(B) gt I^(@)` . their genotype and blood groups are given in the table .