Why is my son blood group O?

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john white

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Why is my son blood group O?
« on: 05/05/2009 15:30:03 »
john white  asked the Naked Scientists:
Hi My blood group is 0 neg and my husband is A   my son has just found out that he is 0  how .

How can this be as I thought children always inherited one of the parents group?
What do you think?


Offline RD

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Why is my son blood group O?
« Reply #1 on: 07/05/2009 01:41:46 »
The "neg" bit of "O neg" refers to the Rhesus factor: "O neg" means blood group O, Rhesus negative.

Individuals either have, or do not have, the Rhesus factor (or Rh D antigen) on the surface of their red blood cells. This is usually indicated by 'RhD positive' (does have the RhD antigen) or 'RhD negative' (does not have the antigen) suffix to the ABO blood type.


So a Rhesus positive child can be born to a Rhesus negative mother if the biological father is Rhesus positive.
« Last Edit: 07/05/2009 01:53:28 by RD »


Offline Jessica H

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Why is my son blood group O?
« Reply #2 on: 07/09/2009 21:20:02 »
The Rh factor (plus or minus) is a seperate gene from the antigens (A,O,B,AB bloodtypes). 

So the above explains the Rh factor.

Then on to the allele for antigens-> type O means that you and your child have two recessive genes for the antigens.  Your husband must also carry the recessive gene, but A is dominant to the recessive gene, so his blood type is A.  So you passed on one recessive gene and your husband passed on the other.