Xref: utzoo sci.bio:1571 sci.med:7655
Path: utzoo!utgpu!attcan!uunet!seismo!sundc!pitstop!sun!decwrl!purdue!haven!uvaarpa!mcnc!ncsuvx!ncsugn!emigh
From: emigh@ncsugn.ncsu.edu (Ted H. Emigh)
Newsgroups: sci.bio,sci.med
Subject: Re: Blood Questions
Message-ID: <5536@ncsugn.ncsu.edu>
Date: 4 Nov 88 13:27:28 GMT
References: <10241@ihlpa.ATT.COM>
Reply-To: emigh@ncsugn.UUCP (Ted H. Emigh)
Organization: Genetics, North Carolina State University, Raleigh, NC
Lines: 54

In article <10241@ihlpa.ATT.COM> krista@ihlpa.ATT.COM (Anderson) writes:

>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?

No, but the testing procedures are not 100% accurate.  It is possible to
test Rh+ one time and Rh- another time.

>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.

The smallpox virus crossreacts to some extent with anitbodies to group
A antigens because of similarity in antigenic structure.  Therefore, type
A people would produce antibodies to smallpox less effectively than people
who are not A or AB.  This may explain why there is a very high frequency
of type O in Iceland (Ann. Hum. Genet. 1985, 49:275).

There is a connection with virtually all antigenic blood types (as well as
the histocompatibility loci) and various diseases -- most likely because of
the antigenic similarities.  In most cases, the effect is slight -- with
notable exception for HLA.

>    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.

This appears to be backward from the way it should be.

>    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.

Any good Human Genetics Textbook will give examples.  Examples of
good textbooks are:
Hartl,  Human Genetics
Sutton, An Introduction to Human Genetics (4th Edition)
Another good book is by Mutolsky, but I seem to have lent my copy, so
  I don't have the title  -- no doubt it is "Human Genetics"


-- 
Ted H. Emigh, Dept. Genetics and Statistics, NCSU, Raleigh, NC
uucp:	mcnc!ncsuvx!ncsugn!emigh	internet:  emigh@ncsugn.ncsu.edu
BITNET: emigh%ncsugn@MCNC.UUCP  or  emigh%ncsugn@ncsuvx.ncsu.edu