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# Your father's blood type is O+ and your mother's blood type is A+, is there a chance that you can become AB?

I NEED TO FIGURE IT OUT... I'M CONFUSED...

me and my siblings are all in AB+ group, but our father is O+ and our mother is A+... i just had the blood typing yesterday in our lab... so confused...

5 years ago

me and my siblings are all in AB+ group, but our father is O+ and our mother is A+... i just had the blood typing yesterday in our laboratory class in Anatomy and Physiology... so confused...

5 years ago

Member since:
05 June 2007
Total points:
44,992 (Level 7)

Nope. ABO blood type, and Rh factor (the + and -) are coded for by different genes, so they are separate from one another. I'll talk about ABO first.

Type A and B are always dominant to (and will express over) type O. If you have two copies of the O gene, you'll be type O, but if you have an A and an O you'll be type A.

Type A and B are codominant, though. In other words, if you have one copy of the A gene, and one copy of the B gene, then your blood type will be type AB.

When reproduction occurs, the offspring gets one copy of each gene from its mother, and one copy from its father. We know what the blood types of the parents are, so we can narrow down their genotype and determine which genes they can pass on. The father's blood type is O. We know that O is recessive, so that means his genotype must be OO, and therefore he can only pass on an O gene to his child. The mother's blood type is A, which is dominant, meaning her genotype can be either AA or AO (we can't narrow it down without more information). That means she can potentially give an A or an O to her child.

Since the father can only give an O gene, and the mother can give an A or an O, when we figure out all the possible combinations, the child can either have AO or OO. That means the child can either have type A or type O blood.

The Rh factor is simpler, since it's straight Mendelian inheritance. The + denotes an Rh marker on the surface of the cells, and the - denotes the absence. This means that the Rh+ gene is dominant to the Rh- gene. We know both parents are Rh+. Since it's a dominant trait, that means that each of their genotypes could be either ++ or +-. That means that the child could inherit either a + or a - gene from each parent. When you do out all the possible combinations, you get ++, +-, and --. That means the child's blood type could be Rh+ or Rh-.

When you combine the ABO and the Rh factor, the possible combinations are A+, A-, O+, and O-.

This is the in-depth way. There's another way to figure it out. The B in type AB has to come from somewhere. Since B is dominant to O, and codominant to A, you'd always be able to see the presence of the B gene. If the mother had it, her type would be AB. If the father had it, his type would be O. Since neither parent has a copy of the B gene, then the child can't have one either. This quick method only works for type A and B, though - the O gene is recessive, so it can "hide" in either or both parents (as long as they're not type AB) and pop up unexpectedly.
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thank you so much...

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• by aida
Member since:
15 July 2007
Total points:
110,842 (Level 7)
It's my understanding that a couple with those types can have only A or O children. If the mother has the Aa genotype, she could pass the "a" gene to her children, so that they could be type O, but there's nowhere for a "B" gene to come from. Is it possible that, since the typing was done in a college lab, there may have been a mistake? Of course that wouldn't account for your siblings, unless they were ALL mistyped. But since all of you have been typed as AB, I think that, rather than suppose that your father isn't your father, you should have HIM retested. Won't it be a relief if he turns out to be type B instead?

### Source(s):

Second semester college biology
• Member since:
08 July 2006
Total points:
319,044 (Level 7)
Only if your dad is actually Bombay phenotype, and mistakenly typed as O, but that is extremely unlikely.

The most likely case in this scenario is that the lab messed up the results for one of your parents.

The second most likely case is that one or more of your parents aren't your biological parents.
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• Member since:
27 December 2008
Total points:
521 (Level 2)
im pretty sure this is wrong...if you are O+ you can only give a child type O blood and the mother type A can only give A or O

so the only combinations of blood for the child are

AO
or OO

not AB
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• by remowlms
Member since:
13 April 2007
Total points:
40,253 (Level 7)
No, AB can not be one of the types.

In your example, the children could only have type A or type O.
• by Nihilism
Member since:
24 June 2008
Total points:
293 (Level 2)
No, there is no chance of the child being AB. The child CANNOT be O-type. O is recessive and must be present in both parents' genotypes. The only possible blood type the child can have is A.

You cannot be AB and come from an O parent and an A parent. Your father has two recessive O alleles, and if your mother had B in her, she would be co-dominant (AB), as you are.

It's simply impossibe. You may be adopted.
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• Member since:
19 January 2009
Total points:
182,298 (Level 7)
No. Either A or O, depending on your mother's genotype.
• 1 person rated this as good
• by Annie
Member since:
30 January 2009
Total points:
118 (Level 1)
yes blood group of the child can be different from parents
• Member since:
19 January 2009
Total points:
3,254 (Level 4)
maybe have a shower cause u may have BO
• 1 person rated this as good