O+ & O- =B+ blood how...?

Question

I'm O- and my boyfriend is O+ our baby is B+.. we've had a DNA test and she's his.. how did this happen.? Just wondering.

Answer 1

There is another gene which affects the presence of ABO blood groups that is called the "Bombay" gene.



It is possible (though rare) that one of you actually has the Bombay phenotype. This is a recessive trait that basically prevents the expression of the normal ABO blood groups. In standard blood typing, you would show up as O, even though genetically you might be AB or B.



If a DNA test has actually shown that the child is your boyfriend's baby, then you should both be tested for the Bombay trait.



This page talks a bit about this situation. It is rather rare, but it could explain this situation.

Answer 2

Are you sure you didn't cheat on him? From what I know, it is possible for a child to have a different blood type from that of its parents; however, I do not see how two O blood types can make a B blood type. I do, however, see how a positive blood type and a negative blood type makes a positive blood type-- that makes sense; however, the genotype for the O blood type is ii. So, if the combination is ii * ii, how can you possible get the combination IBi or IBIB? Both of the previous combinations are the only possible combinations to give a B blood type. I will continue to research this thoroughly, as I am intrigued by this. You may want to consider the possibility that there was a mistake made.

Answer 3

A. Our red blood cells (and some tissues) have got chemical substances called antigens on their surface and the ability to form these antigens is governed by genes inherited from parents. The pattern of genes we have is called genotype and the form in which it is expressed is called phenotype. It is the genotype (genetic make-up) which decides what the blood group (phenotype) will be.



In the ABO system there are three alleles (one member of a pair or series of genes that occupy a specific position on a specific chromosome): Ia - producing the antigen A, Ib - producing the antigen B and Io - producing neither antigen. IA and IB are co-dominant i.e. if both alleles are present, both antigens (A and B) will be formed on the surfaces of red blood cells and the individual will have blood group AB. Io is recessive and produces neither antigen and thus an individual will have blood group O if two of these alleles are present. The genotypic make-up can have 6 possibilities resulting in the following phenotypes:



Ia Ib - AB, Ia Ia - A, Ia Io - A, Ib Ib - B, Ib Io - B, and Io Io – O





Read more at: http://doctor.ndtv.com/faq/ndtv/fid/36640/Can_a_child_have_a_blood_group_different_from_hisher_parents.html?cp

Answer 4

Somebody's blood has been mistyped!!

Yes, one of you COULD be Bombay, but that is extremely unlikely.

A blood typing error is a lot more likely . . .