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Path: utzoo!watmath!clyde!burl!ulysses!allegra!sjuvax!mccann
From: mccann@sjuvax.UUCP (mccann)
Newsgroups: net.motss,net.bio
Subject: Re: gay genes
Message-ID: <1162@sjuvax.UUCP>
Date: Thu, 23-May-85 15:40:30 EDT
Article-I.D.: sjuvax.1162
Posted: Thu May 23 15:40:30 1985
Date-Received: Sat, 25-May-85 09:24:13 EDT
References: <4086@allegra.UUCP> <1901@ut-sally.UUCP> <452@psivax.UUCP>
Reply-To: mccann@sjuvax.UUCP (mccann)
Organization: St. Joseph's University, Phila. PA.
Lines: 21
Xref: watmath net.motss:1720 net.bio:207
Summary: 

>>There are several very different examples of this which come to mind.  One
>>which I can (fuzzily) recall from high school biology is sickle cell anemia,
>>which is deadly when an individual has two of the genes in question but
>>highly beneficial (in tropical climates) to those who only have one, as it
>>reduces susceptibility to malaria.  In this case, the gene has very
>>different consequences in heterozygous and in homozygous form.
>>
>	Actually, the heterozygote(only one copy) sickle cell
>advantage is restricted to tropical Africa, and it is due to
>immunity to African Sleeping Sickness not malaria.

Sickle cell animea does provide an advantage against malaria. The parasite which
causes malaria attacks the hemoglobin in the red blood cell, destroying it and
thus reducing the amount of oxygen carrying cells in circulation (after the 
parasite degrades the Hemoglobin, it reproduces and lysis the cell). Being
heterozygous for the sickle cell trait causes half of a persons hemoglobin to
be different from the 'normal' hemoglobin. If this person contracts malaria,
only half of the hemoglobin in his/her blood is susceptable to the parasite and
they therefor mearly become ill (instead of dying) until a sufficient immune
response is triggered. I don't know about the African Sleeping Sickness.
M. McCann