[Naveed Ijaz]

Naveed Ijaz  asked the Naked Scientists:
   
Hi

We have a myth that an O+ve mums cannot produce an O-ve blood group child. Is it true?
 
My mum is O+ve and I am O-ve; my sublings are all AB.

Please comment

Regards

Naveed

What do you think?

[Don_1]

Naveed Ijaz  asked the Naked Scientists:
   
We have a myth that an O+ve mums cannot produce an O-ve blood group child. Is it true?

No.

[rosy]

Your being O -ve is entirely normal for an O +ve mother. For a single gene effect like this, you either make the Rh protein or not... each of us has two genes, one from each parent, so if your mother has one "+" gene (which leads to making the protein) and one "-" gene (which doesn't, but doesn't stop the "+" gene from doing its stuff) she'll be Rh+ve since she will produce some of that protein, but if you inherit her "-" gene and another "-" gene from your father, then you won't make any of the Rh protein and will be Rh-ve.

The second part of this answer is using first year undergraduate cell biology to speculate at an explanation.... I may be missing some subtle point that explains this..

Your siblings being AB is more surprising, since that's another single gene thing, and each gene is "A", "B" or "O" - A makes an A protein, B a B protein and O no protein. Your mother is O and so has no "A" or "B" genes, she must have two "O" genes. You also have two "O" genes, one from each parent. Your siblings will also have one gene from each parent, but if they can't have inherited a gene directly from your mother, I guess one possibility is that some gene crossover occured (it does, sometimes) so that they inherited half of each of your mother's two genes to make a functioning protein-generating gene. Which would be pretty unusual, I think, if you have more than one sibling who is AB. (If you were asking about your father's genes I'd be more wary about saying this since the most obvious solution would be to question their parentage, but as it's your mother who's O that's not an issue).