ABO blood grouping is controlled by gene I, which has three alleles and show codominance. There are six…
ABO blood grouping is controlled by gene I, which has three alleles and show codominance. There are six genotypes. How many phenotypes in all are possible?
Six
Three
Four
Five
Solution
In $\mathrm{ABO}$ blood group system, inheritance of grouping is controlled by a single autosomal gene on chromosome-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, 4 blood groups (phenotypes) have been differentiated, ie, $A, B, A B$ and $O$ blood groups.