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Archiver > BlackSheep > 2001-06 > 0991695836


From: "Sherri Hall" <>
Subject: Re: Re:[BS-L] Blood types
Date: Mon, 4 Jun 2001 19:04:44 -0400
References: <5.1.0.14.2.20010604111123.00a16ec0@mail.earthlink.net>


Debbie,

This is the perfect example of what I was talking about with family studies.
If your father is "O", that means he has "OO" coding on his cells (no
antigens of A or B). Since you are also an "O", you would have had to
inherit an "O" gene from your mother as well as your father, so your mother
must have been an "AO". No routine test would have detected this, as in the
lab, an "AA" and an "AO" blood type appear the same.

Since your sisters are "A", they are actually "AO", as is your mother. This
means that either one of them can contribute the "A" type or the "O" type to
their offspring.

The positive (+) and negative (-) Rh types are completely independent of the
ABO type. When we talk of your "blood type", we usually are actually
referring to the combination of the ABO and Rh, but they are inherited
completely independently.

With the Rh type, you either have the gene/antigen, or you don't. We blood
bankers refer to the Rh antigen as the "D" antigen, and the lack of the "D"
antigen as "d". In order to be an Rh type of negative, again, you would
have inherited 2 instances of "not" having the antigen (dd). The positive
type could have either inherited the antigen from both parents, (DD), or
from only one, with the other donating the placeholder (Dd).

Again, if the Rh gene is inherited from either parent, that will be
interpreted as a "positive" Rh type. You may have 2 parents that have a
"positive" Rh type, but if they are both (Dd), they could actually have a
child whose Rh type is negative. To add confusion to this whole puzzle,
there are actually 6 "pieces" of the "D" antigen, and you may have all, or
just some of the pieces. If you only have some of the pieces, you may
actually be considered a "weak D", and the cells only give a positive result
in the lab when enhancements to routine testing are employed.

The problem with mis-matched Rh types in mothers/babies occurs if the mother
is Rh negative, and the child is Rh positive.
The D antigen is the one that is most likely to induce an immune response,
causing an antibody to form against it, and this antibody will cross the
placenta. This is of great importance in transfusion and pregnancy, as it
can actually cause a severe transfusion reaction or hemolytic disease of the
newborn (HDN), and may even result in death. To develop either, you would
have to be Rh negative, and to have been exposed to the antigen in order for
the initial antibody response to be triggered. The exposure could be just a
minor bleed during pregnancy (not even recognizable), or transfusion of a
portion or entire unit/units of blood. You would not have a reaction during
the original exposure, but the antibody (anti-D) would develop over the next
few days/weeks. A second exposure, no matter how small, could trigger a
major reaction, even possibly death ( of the patient or fetus).

Because HDN caused by Anti-D used to result in so many infant deaths, the
development and use of RhoGam has revolutionalized the management of these
patients. (RhoGam is actually anti-D that is given as an injection as a
preventative measure.) A mother that is Rh negative will be given RhoGam if
the spouse/partner/father of the fetus she is carrying is Rh positive, or if
the type is unknown. This is done as a precaution, so that if there is a
bleed in utero, the antibody that was given in the RhoGam shot would be coat
the foreign cells, and fool your body into believing it has already been
produced. An additional shot/shots would be given after the baby is born or
if there is a miscarriage.

There is no problem if the mother is Rh positive and the child is Rh
negative.

(Is it clear as mud yet?)
Sherri
----- Original Message -----
From: "Debbie & Jeff Woolard" <>
To: <>
Sent: Monday, June 04, 2001 12:20 PM
Subject: Re:[BS-L] Blood types


>
> I found this very interesting, but a little confusing. The reason
> for my confusion, my Mom is type "A", my father is type "O-". Now if
> I was reading the above correctly, my blood type should have been an
> "A" (or "A-") but it's not, my blood type is "O-".
>
> I now this interesting, because both of my sister take after Mom, one
> is "A" and one is "A-". Maybe this explains why I've always been the
> "oddball" in my family! I've always had to be different than them.
> <g>
>
> Debbie Woolard
>
>
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