Moorad Alexanian <alexanian@UNCWIL.EDU> wrote:
> What is the developmental genes difference between woman and man?
> How feasible is it to turn a man into a woman? I suppose it should
> be easier than turning a man into a chimp or vice versa.
>
> Moorad
>
You're quite right that the essential genetic differences between men
and women are much smaller than between humans and chimps. In humans
and other mammals, the male sex determination switch is controlled by
a single gene on the Y chromosome, SRY (sex-determining region Y).
Expression of this gene is believed to initiate a cascade of gene
interactions leading to the development of testes in the fetus and
thus switching fetal development from the female default path to male.
The clinching evidence for the controlling role of SRY in sex
determination came from an experiment of the kind you suggest -
although carried out in mice rather than humans. When SRY was
introduced into female (XX) mice as a transgene, the fetuses
developed as males (Koopman P, Gubbay J, Vivian N, Goodfellow P,
Lovell-Badge R. Male development of chromosomally female mice
transgenic for SRY. Nature 1991; 351:117-121.)
Also, although for both ethical and technical reasons the same
experiment has not be carried out in humans, studies have noted
both XX males (due to a translocation of an SRY-containing part of
the Y chromosome) and XY females (due to various point mutations in
SRY).
In reference to evolution, it reinforces the point that relatively
small genetic changes can have profound effects on development.
Calum
--Calum MacLeod Tel: +44 1382 562731 Scottish Crop Research Institute Fax: +44 1382 562426 Invergowrie Dundee DD2 5DA Scotland U.K.