Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!gatech!mcnc!decvax!ima!cfisun!lakart!dg
From: dg@lakart.UUCP (David Goodenough)
Newsgroups: sci.bio
Subject: Re: Are blood types inherited?
Message-ID: <661@lakart.UUCP>
Date: 18 Aug 89 22:21:51 GMT
References: <4250@orca.WV.TEK.COM>
Distribution: usa
Organization: Lakart Corporation, Newton, MA
Lines: 43

kris@maui.WV.TEK.COM (Kristen McCormick) asks:
> Can a father with type A positive blood and a mother
> with AB negative (I think) have a child with O positive blood?
> If it helps any, the other child has A positive.

Nope - it is not possible. There are three genes for blood type (the
O A B AB bit, positive and negative are "handled" elsewhere):
O, A and B. A and B are both dominant over O, but are "co-dominant"
when together. Or to put this another way: there are six possible
combinations of O, A and B:

OO	O blood type
AA	A blood type
BB	B blood type
OA	A blood type
OB	B blood type
AB	AB blood type

Now, if one parent is AB, that parent will always pass on either an
A or a B gene, thus leading to either A or B or AB in the child.

Hence an AB parent cannot have an O child. This does not even begin
to address the Rhesus factor (positive or negative) - I believe that
pos is dominant over neg, but am not as sure: the Bio I took in
High School only covered A, B, and O.

> My husband and I both have O positive, and so does our daughter,
> so I'm assuming heredety has something to do with it. 

Correct - I think _ALL_ your offspring will be O pos, however if
negative is recessive to positive, it is possible for you to have
an O negative child.

> But is it always? Is it like, absolute, or are there dominant
> and recessive like eye color? Anyone?

Yep - as I said above O is recessive to A and B, and I think negative
is recessive to positive - perhaps someone else can say more about
+ve and -ve - I'd kind of like to know myself
-- 
	dg@lakart.UUCP - David Goodenough		+---+
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