Xref: utzoo sci.bio:1576 sci.med:7692
Path: utzoo!utgpu!watmath!clyde!att!ihlpa!krista
From: krista@ihlpa.ATT.COM (Anderson)
Newsgroups: sci.bio,sci.med
Subject: Blood Questions
Message-ID: <10241@ihlpa.ATT.COM>
Date: 2 Nov 88 19:02:18 GMT
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 28

<>
I have two blood questions:

1.  In my parents' family of 5 children, 3 are Rh positive, 1 is Rh
negative, and 1 says he used to be positive, but now is tested as
negative.  I don't think it's possible to change Rh factor, is it?

2.  I read in _Encyclopedia_Britannica_ that the A factor helps give
immunity against smallpox and the B factor helps protect from
certain kinds of cancer.

    Since I've read about Native Americans and ethnology, I'm
surprised I've never heard this before.  Incidence of types A and B
is very low among Native Americans, and by 1700, 80-90% of Native
Americans had died of various European diseases, esp. smallpox.

    The encyclopedia went on to say that the Blackfeet tribe had
about 59% type A at the time that it was measured.  The authors
hypothesize that a smallpox epidemic devastated the majority of
people with O type.  I have read from other sources that this tribe
has a high incidence of type A, unlike any other American tribe.

    My question is, has anyone else read about type A to smallpox
correlation?  One doesn't usually doubt the _Encyclopedia_Britanica_!
If anyone is in the know, it would be interesting to see the
relationships of blood factors to phenotypic expressions.

Thanks in advance.  Krista A.