Clue to anti-male gene action :
An extra gene can stop boys being boys
5 July 2008
For
background information, view here
For images,
view here.
Researchers at Prince Henry’s
Institute in Melbourne have discovered how an extra copy of a gene halts the
process of becoming a boy.
Their work may lead to
earlier diagnosis and better management of a condition known as disorder of sex
development (DSD) whereby one in 4500 babies is born with ambiguous or
incomplete genital development, making it difficult for parents and doctors to
identify whether the child should be raised as a boy or a girl.
The gene, known as DAX1,
regulates sexual development. An extra copy of DAX1 in male babies blocks the
development of the testicles entirely, and this is responsible for some cases of
DSD, says PhD candidate Louisa Ludbrook who undertook the research.
Using
cells in culture, the researchers found that increasing copies of the gene DAX-1
could block the production of a potent male factor, called SOX9. This factor is
important in most animals with testicles.
“A common
requirement for testicle development, conserved between species as diverse as
humans and reptiles, is an increase in production of the gene SOX9. When SOX9
production reaches a certain level, testicles, rather than ovaries, will
develop,” says A/Prof Vincent Harley,
head of the Human Molecular Genetics unit at Prince Henry’s Institute.
“By knowing exactly the point
when development of the testicles is blocked, we can help parents and doctors
decide on the best treatment options for these kids, be it hormone therapy or
surgery,” says Louisa.
“And
studying these kinds of conditions also helps us understand the broad sweep of
human sexual development,” says Louisa.
The
discovery was presented at The World Congress on Hypospadias and Disorders of
Sex Development held recently in Rome.
Louisa received a Monash
University postgraduate travel award to study DAX1 in mice at the UK National
Institute of Medical Research, London, in the laboratory of Dr Robin
Lovell-Badge, a leading expert in the field.
Louisa Ludbrook is one of 16
early-career scientists chosen for Fresh Science, a national program sponsored
by the Federal and Victorian governments. She is presenting her research to the
public for the first time.
Media contacts: Louisa Ludbrook
on 0403 197 792,
Louisa.Ludbrook@princehenrys.org;
Niall Byrne on 0417 131 977 or
niall@freshscience.org,
and Ian Muchamore on 0415 551 705.
Background
Abstract
Presented at 2nd World Congress on
Hypospadias and Disorders of Sex Development organised
by the International Society for Hypospadias
and Intersex Disorders (ISHID), Rome, Nov 2007.
Images
Click on image for higher resolution image for download,
highest res available on request
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Louisa Ludbrook in the Lab.
Photo: Photographic Unit, Monash University
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A/Prof Vincent Harley (supervisor and Head of
Human Molecular Genetics Lab, PHI) and PhD candidate Louisa Ludbrook
Photo: Sue Panckridge
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A
baby’s sex is determined at conception. A girl has two X chromosomes
leading to ovaries and female genitals. A boy has one X and one Y
chromosome, leading to testicles and male genitals. If an XY embryo gets
an extra copy of the DAX1 gene, a disorder of sex development (DSD)
arises. Testicles do not properly form and genitals may look female or
appear ambiguous.
Credit: Louisa Ludbrook |
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