Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!portal!cup.portal.com!mmm
From: mmm@cup.portal.com (Mark Robert Thorson)
Newsgroups: sci.bio
Subject: Re: Genetic Mosaic Humans
Message-ID: <24831@cup.portal.com>
Date: 8 Dec 89 21:37:05 GMT
References: <2630003@hpcilzb.HP.COM> <24804@cup.portal.com>
Distribution: na
Organization: The Portal System (TM)
Lines: 9

In the biology text I used in college, it was mentioned that there is a
genetic condition which causes the absence of skin hair, and that in some
women this can have a sort of patchwork appearance due to different
expression of the X-chromosome.  In women, one of the two X-chromosomes
is not needed, and remains bundled up.  (The unused chromosome is easily
seen using staining and a microscope.  Used as a test for gender, in those
cases where it is uncertain.)  Because the defective gene is on the X-
chromosome, expression of skin hair reveals something like a genetic
mosaic, in that it reveals which X-chromosome is being expressed where.