A newborn is typed as Group O; her mother is Group A. Determine the maximum number of theoretical blood types that the father could be to produce a child of this ABO type.

Question

Quizplus · Accepted Answer

A child with blood type O must inherit an O allele from each parent. The mother, being type A, could be either genotype AO or AA. Since the child is type O, the mother must be AO, passing the O allele. The father can be A (AO or AA), B (BO or BB), or O (OO), making three possible blood types. AB is not possible because the child would then inherit an A or B allele, not resulting in type O.

A Newborn Is Typed as Group O; Her Mother Is