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Name: Judy
Status: Other
Grade:  Other
Location: TX
Country: United States
Date: May 2006

My father is mother is O+..both my brother and I are O+. Yes he is our father. With blood typing being a clearly defined science, how can this be explained?

My husband is A+, and I am O+..our daughter is A-. I am told this happened because my father being a recessive negative. Does this mean that both my husband and I are carriers?

It is possible that both your mother and father carry the recessive gene for the Bombay phenotype. This gene, when homozygous, results in the absence of the O or H antigen which is the precursor of both the A and B antigen. In other words, both you and your brother may have inherited the A or B antigen from your father but not express it. You and your brother should be tested for the H antigen which produces the O blood type. If you lack the H antigen, then you have the Bombay phenotype, and this would explain why you and your brother don't express the A or B anitgen which you should have inherited from your father. If you lack the H antigen, you can only receive a blood transfusion from another person with the Bombay phenotype, which is rare. If your are a Bombay phenotype, you should store some of your own blood for a possible future transfusion.

The fact that your daughter is Rh(-), means that she inherited the recessive Rh(-) gene from both you and your husband.

In your question you mentioned that your father is your biological father. How do you know this? Has DNA testing been done?

Regards, Ron Baker, Ph.D.

There are two explanations for AB father and O mother. First, I would have all the blood types rechecked. I had a situation like this a few years ago where I had a mother and daughter both in a medical assisting class. We were learning to do blood typing and they were concerned because their father/husband had an incompatible blood type. They went home and asked him how he knew his blood type and he said he had had it tested in the Army decades ago. I gave them some blood typing materials to take home, and sure enough he had a different blood type than he thought. Another possibility is what is known as the Bombay phenotype. Blood phenotype is actually the result of more than one gene. The antigens (ie. A, B, and O) are coded for by one gene, but there is a gene for an enzyme that actually "sticks" the antigens on to the surface of the red blood cell. Let's call this the H gene. Rarely, someone will hh, in other words recessive for the enzyme, and therefore the antigens don't get added. So even though one would have a genetic blood type, it wouldn't show and you would appear to be type O. There is a blood test for this, but it isn't tested for routinely when you have your blood typed.

As far as a type A and type O mom having type A kids, yes that is possible if the type A person is a carrier of the O gene.


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