Question
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.?
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Six
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Three
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Four
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Five
Solution
C.
Four
In ABO blood group system, inheritance of grouping is controlled by a single autosomal gene on chromosome-9 with three major alleles A, B and O) (IA, IB and Io). The 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, AB and O blood groups.
