Question

The mother has A+ blood group the father has B+ and the child is A+. What can be the possibility of genotypes of all three, respectively?
(A) I AI A | I Bi | IBi
(B) I AI A | I Bi | I Ai
(C) I Bi | I AI A | I AI B
(D) I AI A | I BI B | I Ai
(E) I Ai | I Bi | I Ai
Choose the correct answer from the option given below:

• A. C and D
• B. D and A
• C. A and B
• D. B and E

Answer 1

Answer: (D)

B and E

Answer 2

Let's consider the ABO blood group system and the Rh factor separately.
ABO blood groups:
Mother (A+): Possible genotypes are $I^AI^A$ or $I^Ai$.
Father (B+): Possible genotypes are $I^BI^B$ or $I^Bi$.
Child (A+): Possible genotypes are $I^AI^A$ or $I^Ai$.
Since the child is A+ , they must have received at least one $I^A$ allele. Since the father is B+, if the child received an $I^A$ allele from the mother, then they must have received an $i$ allele from the father. This means both the mother and father must carry the $i$ allele, so both must be heterozygous. Therefore, for the ABO blood group system alone, the genotypes must be $I^Ai$, $I^Bi$, and $I^Ai$ for mother, father, and child, respectively.
Rh factor:
Mother (+): Possible genotypes are ++ or +-. **
Father (+): Possible genotypes are ++ or +-. **
Child (+): Possible genotypes are ++ or +-.
Since both parents are Rh-positive, they can either behomozygous (+++) or heterozygous (+-). The child can inherit either a + or – allele from each parent, resulting in either ++ or +-.
Therefore, since the child is A+ , and both parents are positive, the only possible genotype combination from the provided options that yields an A+ child is: $I^Ai$ | $I^Bi$ | $I^Ai$, which are options B and E.