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Date of last update: 10/12/2017.

Forum Name: Hematology Topics

Question: questioning paternaty due to blood types i am 19/m

 evidentloss - Mon Oct 22, 2007 8:45 pm

me and my fiance were wondering if you could tell us if it were possible for a white female with slight german/irish decent with o+ blood type and a white male with slight irish/and very slight cherokee decent with a+ decent could have a baby girl with a- blood type? if you can't answer the question do you have any suggestions the where i could find the answer? thank you for you time.
 Dr. Chan Lowe - Mon Oct 22, 2007 9:01 pm

User avatar Hi Evidentloss,

There are two different factors to consider. First, the A, B, O or AB status of the baby. Then the positive or negative status.

Each parent has two copies of the genes, with each passing one of their genes on to the baby. Regarding the ABO part, A and B are both known as dominant blood types. If a person has an A or a B gene that part will be in the blood type. O is a recessive type. For a person to be O there must be two O genes. If a person is A and O the blood type is A, if it is B and O the blood type is B. If a person is A and B the blood type is AB. So, for the baby in question, with one parent A and the other O having an A baby we would deduce that the baby has received the A from one parent and the O from the other parent (the only option in this case since O parent must be O,O). So, the baby will have the genes A and O making an A blood type.

Now the +,- part. + is the dominant gene. If it is present the baby will be blood type +. So, is it possible for two + parents to have a negative baby? There is one way. Each parent must have one copy of the + gene and one copy of the negative gene (+,-) so that there is a possibility of the baby receiving the negative gene from both parents creating a negative blood type with two positive parents.

I hope this isn't too confusing. To summarize, it is possible for an A+ and an O+ couple to have an A neg. baby.

Best wishes.

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