MadSci Network: Medicine

Re: I would like to know my husbands bloodtype & why our daughter had yaundice?

Date: Mon Jul 17 17:16:34 2000
Posted By: Paul Odgren, Instructor, Cell Biology, University of Massachusetts Medical School (Dept. of Cell Biology)
Area of science: Medicine
ID: 958185521.Me

Hi Ann,

I just spotted your question awaiting an answer. Sorry it took so long.

First, your physician can order a blood type done on your husband, but he 
might have to pay a fee. Alternatively, if he donates blood at a local 
hospital or the Red Cross, he can check back with the blood bank's medical 
director or other appropriate staff within a couple of days of his donation 
and they can tell him, since all donor blood has to get typed before use. 
That way he gets the information for free and he also does a public 

As to your daughter's jaundice, here's how it works. The difference between 
type A, B and O blood is whether there is a particular type of sugar 
molecule on the end of a sort of molecular chain on the surface of your red 
blood cells. This trait is determined by a gene you inherit from your 
parents. If it's one kind of sugar, you're type A. If it's another kind, 
you're type B. If you don't have either one, you're type O, and if you have 
some of both kinds, you're type AB. It so happens that these same sugar 
molecules are found in food, dust, and a lot of other places, and your body 
becomes immune to the ones you don't have as part of your own self. So your 
immune system makes lots of antibodies against these molecules (things that 
elicit an antibody response are called "antigens"). Antibodies bind to 
foreign substances in your body and help eliminate them. So if you're type 
A, you make anti-B because the B antigen is not a normal part of your body. 
If you're type B, you make anti-A. If you're type O ("universal donor"), 
you don't have either A or B antigen in your own body, so you make anti-A 
and anti-B, and if you're type AB ("universal recipient"), you don't make 
either one. The + and - refer to a different system of blood group 
molecules, the Rh system, which is involved in some very serious cases 
of newborn jaundice, but that's another whole story.

Now, antibodies to A and B are mainly made up of a class of antibody 
molecules called IgM. IgM antibodies cannot cross the barrier of the 
placenta between the mother's and baby's circulation. But some antibodies 
are of the IgG class, and these do cross the placenta. This protects the 
baby from everything the mother is immune to, and it gives newborns a kind 
of 6-month warranty during which the antibodies they got from Mom protect 
them from many infections and diseases. Once the antibody levels drop down, 
then the kids are on their own, and seem like they catch every cold that 
comes through town. It so happens that the levels of IgG antibody against A 
or B antigen can be fairly high in type O people. That antibody can cross 
the placenta and kill red blood cells in the baby's circulation, and the 
orange pigment called bilirubin builds up in the baby's circulation as a 
result. Bilirubin is toxic to the nervous system at high levels. Before 
birth, the mother's liver handles this with no trouble, but the baby's 
liver is small and can't handle the load after birth, and this leads to 
jaundice - usually mild and easily handled by ultraviolet light, which 
de-toxifies the bilirubin. If the problem is more severe, a transfusion can 
manage it. You being type O and your daughter type A would be a classic 
case of neonatal jaundice due to ABO incompatibility. I hope this answers 
your question.

Paul R. Odgren, Ph.D.
Cell Biology
University of Massachusetts Medical School

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