Question $32(2\mathrm{.}5$ points$)$

A person with Type $AB$ blood $($genotype $I^A{I}^B)$ has a child with a person who has Type A blood $(($:${|}^A{|}^A\}.$ When the child's blood type is tested with standard antibody blood typing, it is Type O $.$ The parents are understandably confused. What can you do to reassure them that they are both the biological parents of the child?

$($The letter designation for blood type gene is the letter I, and then the specific allele is designated as $A$ or $B$ or $O.$ So a person with type $AB$ blood has alleles $I^A$ and $I^B$ so their genotype is ${|}^A{I}^B|.)$

Let the parents know that you will do a test that identifies whether or not the child produces the epistatic H protein in their RBCs$,$ and if they don't then this would then explain the O genotype.

Let the parents know that you will do the ABO blood test again three times just to make sure the results are correct before you make any conclusions.

There's nothing you can do$,$ so let the parents know that unfortunately one or both of them are probably not the child's biological parent.

Ask the child's doctor if the child received a blood transfusion recently.