Question

Mom is A+. She has 2 children, one is O+ and the other is B-. (Note: Rh+ is RR or Rr, and Rh- is rr) What are the father’s possible genotypes?

Answer 1

Answer:

• The blood group of the father must be B.
• The genotype of blood group would be $I^{B}i$.
• The Rh factor of the father can either be positive or negative.
• Thus, the genotype of Rh factor of father would be either Rr or rr.

Rh factor:

The phenotype of the mother Rh factor is positive. Thus, she can have Rr or RR as her genotype as positive is a dominant trait.

If the genotype of the mother is RR then all the offspring would be positive for Rh factor. However, one of the offspring is Rh negative, that means the mother must be heterozygous that is, Rr.

The genotype of the father can either be Rr or rr in order to produce offspring with positive as well as negative Rh.

Blood group:

The blood group of the mother is A. Thus, the genotype can either be $I^{A}I^{A}$ or $I^{A}i$.

However, the blood groups of the children are O+ and B+.

Thus, the genotype of the mother must be heterozygous that is $I^{A}i$.

The blood group of the father must be B with genotype $I^{B}i$ in order to produce offspring with blood group O and B.