ABO blood groups in humans are controlled by the gene I. It has...

In ABO blood group system, inheritance of grouping is controlled by a single autosomal gene on chomosome 9 with three major alleles $\mathrm{A}, \mathrm{B} and$\mathrm{O}\left($\mathrm{I}$^{\mathrm{A}}, $\mathrm{I}$^{\mathrm{B}}\right. and \left.$\mathrm{I}$^{\mathrm{O}}\right)$. The$\mathrm{ABO}$blood group system has at least 6 genotypes. On the basis of presence or absence of antigens and antibodies, four blood groups (phenotypes) have been differentiated-A, B, AB and$O$ blood groups.