Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!psuvax1!psuvm.bitnet!cunyvm!barilvm!bimacs!kanov
From: kanov@bimacs.BITNET (Mechael Kanovsky)
Newsgroups: sci.bio
Subject: Re: twins
Message-ID: <775@bimacs.BITNET>
Date: 30 Jan 89 15:48:09 GMT
References: <1046@jimi.cs.unlv.edu>
Reply-To: kanov@bimacs.UUCP (Mechael Kanovsky)
Organization: Bar-Ilan University, Israel.
Lines: 29


In article <1046@jimi.cs.unlv.edu> robert@jimi.cs.unlv.edu (Robert Cray) writes:
>I was reading a genetics book a while ago and came across "...almost all
>MZ twins are same sex...".  Thinking about it, I can't figure out how you
>could have MZ twins of different sex, anyone know?  Was the author just
>hedging?
>
>                                        --robert

  Probably he is, but I still can think of a long shot of a case where
MZ (monozygot) twins will be of different sexes.
  If in one of the twins we have a mutation that will occur on the Y
gene and for that reason there will be a defect in the membrane
protien that recognizes testosterone what you will get is an XY
female. Actualy there are a few other genetic defects where XX will
have male characteristics and XY where they will be female. But I
can't think of a case where the MZ twins will be of different sexes
and they will both be normal.


--

Mechael Kanovsky     : BITNET  kanov@bimacs.bitnet
Math & CS Dept.      : UUCP    uunet!mcvax!humus!bimacs!kanov
Bar-Ilan University  : ARPA    kanov%bimacs.bitnet@cunyvm.cuny.edu
Ramat-Gan Israel     : CSNET   kanov%bimacs.bitnet%cunyvm.cuny.edu@csnet-relay

                           !  You can't propel yourself forward !
                           !   by patting yourself on the back  !



#! rnews           1