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  #1  
Old 12-03-2009
HouseWannabe's Avatar
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RBC Blood typing assays

Here's a question i thought was interesting, let's see if you can get it.

A couple requests blood typing of their 2yr old child (father AB, Rh -ve; mother B, Rh -ve). Results of the hemagglutination assays of the child's blood are as follows:

+ = Hemagglutination, - = No Hemagglutiation

Saline + Child's RBC -
Anti A + Childr's RBC -
Anti B + Childr's RBC +
Anti D + Childr's RBC -

Child's serum + Type A RBC +
Child's serum + Type B RBC -
Child's serum + Type D RBC -

Which of the following conclusions concerning the child's parentage is valid?

a. The child is the natural offspring of this couple
b. The mother is the biological mother, but the father is not
c. The father is the biological father, but the mother is not
d. Neither one is the biological parent


what do you think the answer is, and why?
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  #2  
Old 12-03-2009
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It's funny that there's an option saying the father is biological and mother is not
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Old 12-03-2009
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Because the child's RBC has agglutinated with an Anti-B then he must have B antigen on the surface of RBC.
Because the child's RBC has not agglutinated with Anti-D antibodies then there's no D antigen on the RBC surface.
Similarly his serum must have anti-A antibodies as it agglutinated A RBC and should have no Anti-D antibodies as it did not agglutinate D RBCs.
Conclusion: the child is B -ve

Father AB- X Mother Bb- => these possibilities; AB-, Ab-, BB-, Bb-
So there's 50% chance that the baby will be B- and the best answer is choice A.

However, they should not say the "child IS the natural offspring" because blood grouping is only suggestive of paternity and is not conclusive and the options should say the child Maybe or probably or likely ...etc
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Old 12-03-2009
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yes ..agree .....

we can't conclude that the child is the natural offspring of the couple ....we can say that the child maybe or can be their offspring....

from the test result, there are
B Ag on the child's RBCs with no D antigen on them
Anti A Ab in the child's serum

so the child's blood group is BO Rh- which can be the result of (AB Rh- X BO Rh-)......the answer is A
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  #5  
Old 12-03-2009
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I think it is A too, but technically, B could also be true especially if it actually stated "The Mother is the biological mother but the father may or may not be the biological father," since the child could have inherited his B-ve blood group either from his AB-ve father as well as from a BO-ve mailman.

No judgements though...
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Old 12-03-2009
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Quote:
Originally Posted by ashishkabir View Post
I think it is A too, but technically, B could also be true especially if it actually stated "The Mother is the biological mother but the father may or may not be the biological father," since the child could have inherited his B-ve blood group either from his AB-ve father as well as from a BO-ve mailman.

No judgements though...
hahaha, what do you mean by mailman? do you think that the mother has a relation with the guy that delivers the mail
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Old 12-03-2009
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Quote:
Originally Posted by Firas View Post
hahaha, what do you mean by mailman? do you think that the mother has a relation with the guy that delivers the mail
Yeah... It's sort of a standard joke Mailman / milkman / neighbour etc..

I'm just kidding around.
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Old 12-03-2009
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Smile

lol, no it wasn't the mailman, the correct answer is A.

Firas was right in saying it should be a probable statement; I had to change the phrasing of the question and the mutliple choices so there wouldn't be a problem of "plagiarism" just incase...
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