A man with heterozygous genotype for blood group B marries a woman with heterozygous A, what percentage (%) of their children would be universal donor?

A man with heterozygous genotype for blood group B marries a woman with heterozygous A, what percentage
(%) of their children would be universal donor?

Answer Details

Neither the man nor the woman has the genotype for the O blood group, which is the universal donor. However, their children can inherit an O blood group allele from both parents and have the O blood group.

To determine the percentage of their children that would be universal donors (O blood group), we need to use a Punnett square.

The man has the genotype Bb, and the woman has the genotype Aa. When we combine these genotypes in a Punnett square, we get the following:

  | A    a
--|--------
B | AB   aB
b | Ab   ab

From this Punnett square, we see that there is a 25% chance that the child will inherit an O blood group allele from both parents and have the O blood group (shown as "ab" in the Punnett square). Therefore, the answer is 25%.

Note that while the child with the O blood group can donate to anyone, they can only receive blood from another O blood group donor.