Question

A boy has the blood group AB. What is true of the inheritance of this blood group in his case?

Options

• His parents should be one with O group and the other with B group

• His parents should be one with O group and the other with A group

• Both his parents should be with B group

• His father should be A group and mother with B group

Answer 1

His father should be A group and mother with B group

Explanation:

Blood group AB results from inheriting one allele I^A from one parent and one allele I^B from the other parent. Since A and B are codominant, a person with genotype I^A I^B shows blood group AB. Therefore, for a boy to have blood group AB, one parent must have an A allele (blood group A) and the other must have a B allele (blood group B). Other combinations such as one parent with group O and the other with B or A cannot produce AB offspring because O group parents have genotype ii, which cannot contribute A or B alleles needed for AB blood group.