How Do You Know if You Are Bb or Bo Blood Type

-A high school pupil from the U.k.

October 1, 2014

You can end worrying…an A parent and an O parent tin definitely have an O child. In fact, each kid of these parents could accept a 50% run a risk of existence O.

Now this isn't to say that A isn't dominant over O. Information technology is. In fact, it is its authority that caused your O blood type!

Because A is dominant, that means your mother could carry a hidden O. If she does and so when she gets pregnant, each child has a 50% take chances of getting her dominant A and a 50% chance of getting her hidden, recessive O. If the kid gets the O from mom and an O from dad, he or she will have an O blood blazon. This is nigh certainly how you ended up O.

This is the simple answer for how an A mom and an O dad tin have an O child.  To amend empathize what is going on here, nosotros need to take a pace back and call up nigh how our genes work.  Once we exercise that, I retrieve it'll become even clearer where your O blood type came from.

Ii Copies, Different Versions

The part of our blood type we are discussing here comes from the imaginatively named ABO gene.  This gene comes in three different versions—A, B, and O.

Similar most of our other genes, we have two copies of our ABO gene, one from mom and one from dad.  With 3 versions and two copies, here are all the possible gene combinations any of united states of america could have:

Every bit y'all undoubtedly know, at that place is no AO or BO blood blazon.  This is because A and B are dominant over O.  What this means is that an AO claret type looks like A in a blood test and a BO similar B.  We can at present add claret type to our table:

As a side note y'all may take noticed that the AB blood type is made up of an A version (or allele) of the ABO factor and a B version.  This is because A and B are codominant—if you have both you can encounter both in a blood test. Neither is dominant over the other.

OK at present nosotros are fix to tackle your item question.  All we need to do is say that your mom is AO and your dad is OO.

Getting O from A and O

To figure this out I am going to dust off the old Punnett square.  This is a very useful way to effigy out the chances of a kid getting a certain trait.

So the first thing we need to practise is effigy out what mom and dad's versions of their ABO genes are.  This is easy in this case.  Mom has an A and an O and dad has two O's.

The next step is to set up a 2 X 2 foursquare with mom's versions on tiptop and dad's forth the side.  Hither is what your family unit's would look similar:

Next you combine the squares to get each possible genotype for each child.  (Genotype just means the two versions that child has.)  Here is how we practise the offset one:

This first child got an A from mom and an O from dad.  He or she is AO genetically which ways A claret type.  We can at present fill in the rest of the foursquare similar so:

As yous can tell, half the square is AO and half is OO.  This translates to each kid having a 50% risk of being AO and having an A blood type and a 50% chance of being OO and having an O blood type.  Information technology does non mean that if you accept four kids, two will be AO and two volition be OO (click here for more on this).

That is a useful way to figure out the chances and all of the possibilities, but information technology is sometimes a bit as well abstract.  Some other way to show what happened in your particular example is with pictures like this:

Here you can see that dad has two O'south and mom has an A and an O.  Along each pointer is the allele or version that each parent happened to pass to their child.  As yous can encounter, both happened to pass an O which gave the kid an O blood type.

If mom had passed an A instead, then the kid would exist AO and accept an A claret type.  In this instance the kid's blood type depends on mom because dad can simply pass an O.

And so yous managed to be O because A is dominant.  Its dominance allowed your mom'southward O to exist hidden, fix to be seen in you.

By Dr. Barry Starr, Stanford University

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Source: https://genetics.thetech.org/ask-a-geneticist/blood-type-parent-o-blood-type-child