http://www.cbc.ca/health/story/2010/09/15/autism-males-genetics.html?ref=rss
Mutation in some autistic boys found
Last Updated: Wednesday, September 15, 2010 | 2:29 PM ET CBC News
About one in 80 boys that are newborn are autistic, and may need help
learning to communicate. (Vincent Du/Reuters)
A small fraction of autism cases are linked to a gene found on the X
chromosome, a discovery that may help explain why more males are affected by
the disorder.
There is no one gene responsible for autism spectrum disorder, or ASD.
People with the disorder may have mild to severe symptoms that inhibit a
person's ability to communicate and develop social relationships, which is
often accompanied by behavioural challenges.
In some people, however, the disorder has a strong genetic component.
There's also a four-to-one male-to-female gender bias that has long
intrigued researchers.
Now, in Wednesday's online issue of the journal Science Translational
Medicine, researchers at Toronto's Hospital for Sick Children and the Centre
for Addiction and Mental Health report specific genetic alterations on the X
chromosome that increase the risk of developing autism.
Females carry two copies of the X chromosome, whereas males have only one.
Males who would inherit the genetic change from their mother are not
protected, said the study's co-senior author, Dr. Stephen Scherer, senior
scientist and director of the Centre for Applied Genomics at Sick Kids.
"It's important to point out that one in 80 boys that are newborn now are
autistic in some way or another," Scherer said in an interview. "So we've
now identified the genetic cause in one per cent of those individuals, so in
fact it's actually a large proportion of the population."
The newly identified change is found on a gene called Patched 1 or PTCHD1.
To find it, researchers analyzed the genomes of almost 2,250 individuals,
including almost 2,000 with ASD and 246 with intellectual disabilities, as
well as more than 10,000 controls.
Test in the works
The gene is thought to play a role in neurobiological pathways that deliver
information to cells during brain develop, the researchers said.
If the change is identified on the X chromosome and it is passed on to a
boy, which would occur in about half of cases, the likelihood that he will
be autistic is very high, Scherer said.
With the latest discovery, a genetic alteration that leads to autism could
be identified in about 15 per cent of families with autism, Scherer noted.
Blood or saliva tests based on the discovery will probably roll out in the
next year in most places, he predicted.
Its important to communicate the information to families because they often
ask what is the cause of autism in their family, or they want to know the
risk of it occurring in a another child or relative, Scherer said.
"Piece by piece, we are discovering genetic mutations that can cause
autism," said Andy Shih, vice president of scientific affairs for Autism
Speaks, a science and advocacy group based in New York that funded the
research.
"These findings will provide answers for families about what contributed to
their autism," Shih added in a release.
The study was also funded by Genome Canada through the Ontario Genomics
Institute, the McLaughlin Centre, the Canadian Institutes of Health
Research, the Canadian Institute for Advanced Research, the Canada
Foundation for Innovation, Ontario's Ministry of Research and Innovation,
the Ontario Innovation Trust, the Catherine and Maxwell Meighen Foundation,
the National Alliance for Research on Schizophrenia and Depression, the
Ontario's Premier's Summit Award in Medical Research, The Centre for Applied
Genomics, the Chedoke Health Corporation, the Mayberry Family Fund, the
Hamilton Health Sciences Foundation and the SickKids Foundation.
Read more:
http://www.cbc.ca/health/story/2010/09/15/autism-males-genetics.html?ref=rss
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