Can an a negative father and an b positive mother have an ab positive child?

Answer 1

Yes, I will explain how.

A person with blood type AB has one A and one B gene. Only one is passed on to the child. So, for this question, the child got the B gene.

A person with blood type A can have either two A genes (AA) or one A and one O (AO). A is dominant to O, so A is the blood type expressed. Once again, only one gene is passed to the child. The mother in this case must be AO, because an AA mother could only pass on an A to the child. A+B=AB, because A and B are both dominant genes and are both expressed. The mother passed on the O gene.

So, the father is AB, the mother is AO, and the child is BO (type B).

Rh factor is passed on in the same way and also involves dominance. Positive (+) is dominant to negative (-). An Rh+ person can be (++) or (+-). An Rh- person has to be (--). For the child in this question that means both parents must have a (-) to pass on. This tells us that the father is (--) because we know he is Rh negative, and the mother is (+-) because we know she is Rh positive, but she also had to pass on a (-).

Father = AB(--)

Mother = AO(+-)

Child = BO(--)

Answer 2

Yes.

The ABO and Rhesus blood grouping systems (along with nealy 300 other blood grounping systems - Kell, Kidd, Duffy, Lutheran, MNS etc etc) are not connected.

Lets start with the ABO system.

To be group A you must have acquired at least one A gene from one parent. The other parent could have provided aither an A or an O gene. So, someone who has AA or AO genes will type as group A. Similarly, someone who types as group B could carry BB or BO genes.

Next, the rhesus system.

This system comprises 3 components, C, D and E (with corresponding "negative" genes c, d and e). "negative" is in inverted commas because there is no such thing as "d" gene product, it's just convenient to express D negative as d. Further, when we're talking about Rh positive or negative, we're talking about them having (Rh (D) positive) or not having the D gene. Lets look at the parents to make things clearer:

If you inherit D from either parent you will type as Rh Positive. So a child who has a DD positive parent will always be Rh positive, as they will always receive one of those big D's.

If you have an Rh negative parent, they must be dd.

If our DD parent and our dd parent produced offspring, each child would get one D and one "d", and would always type as Rh positive, because of the presence of the D gene.

Now, if our Rh positive parent happened to be Dd, remember, they are typed as Rh positive by virtue of their D gene. However, they could donate either their D gene or their "d" gene to a child. If the other parent is "dd", then the offspring have a 50% chance of being either Rh positive or Rh negative depending on which gene they get from the Rh positive parent.

So now, lets look at your specific case above.

The A neg father could be AA or AO and must be rhesus "dd".

The B pos mother could be BB or BO and could be DD or Dd.

Lets say their child gets Dad's A gene, Mum's B gene, then baby is AB.

Bub will get Dad's "d" and one of Mum's genes. If she's Dd then there's a 50% chance bub will get Mum's D gene.

So, genotypically, Bub could be A (from dad) B (from Mum) ie AB

and D (from mum) and d ( from Dad - ie Dd.

Which would type as AB Positive.

Answer 3

Yes. The child would inherit the B allele from the father and an O allele from his mother, and he would inherit one rh+ allele from the mother, and an rh-allele from his father. The child's genotype would be BO for blood group B, and rh+/rh- for positive rh factor.

Answer 4

Yes, if the father's genes are Ai (A) and Rr (positive), since the mother's genes are B_ (B) and rr (negative), the child can be born as Bi and rr, therefore B negative.

Answer 5

No, an O+ father and an AB+ mother can only have A+ or B+ children.

Answer 6

The child will be A or B or AB, Rh+ or Rh- . So yes, the child can be A-.