Offord Centre leads discovery of genes believed to contribute to autism

February 19, 2007

Researchers at the Offord Centre for Child Studies have led an international consortium in the discovery of one gene and a previously unidentified region of another chromosome as the location of another gene that may contribute to a child’s chances of having autism.

Their findings, based on genetic samples from nearly 1,200 families with two or more children who have autism, were published today in the prestigious journal Nature Genetics.

Led by Dr. Peter Szatmari, Director of the Offord Centre, and Dr. Stephen Scherer at The Hospital for Sick Children, the Canadians are part of the largest genome scan ever attempted in autism research.  Their work is supported by Genome Canada and the Canadian Institutes of Health Research. 

More than 120 scientists from Europe and North America make up the Autism Genome Project, which was launched in 2002 to share data, samples and expertise in an effort to speed up the process of identifying susceptibility genes, those that heighten a child’s risk of having the developmental disorder. 

Using this unprecedented statistical power, the scientists were able to implicate a previously unidentified region of chromosome 11, and neurexin 1, among other regions and genes in the genome. The neurexin finding in particular highlights a special group of neurons, called glutamate neurons, and the genes affecting their development and function, suggesting they play a critical role in autism spectrum disorders.

“The clinical implications of this discovery are unprecedented,” said Dr. Szatmari, who led the committee to decide the phenotypes to be used in analysis, and was instrumental in drafting the memorandum of agreement among the consortium members, who represent 50 different institutions.

“Not only have we found which haystack the needle is in, we now know where in the haystack that needle is located.  This is a major breakthrough in our efforts to better understand the disorder and improve diagnosis and treatment for patients and their families.”

Dr. Szatmari, professor, Vice-Chair of Research, and Head of the Division of Child Psychiatry at McMaster, is a leading expert in autism, one of a number of developmental problems studied by researchers at the Offord Centre.  He and other members of the Centre’s autism team have been responsible for some of the most exciting recent developments in the field of autism research worldwide.

The researchers will now turn their attention to mapping the specific genes that cause autism.

“In essence, we will be looking at the genes to see if there is any abnormality that might cause this complex developmental disorder,” said Dr. Szatmari.  “We also want to know if the genes interact to create a combined effect that is more powerful than each alone, or whether they operate only in certain subgroups of children, such as females, those who are higher functioning, or those who have Asperger Syndrome.”

Autism is a complex developmental disorder affecting roughly one in 165 children, making it the most common form of any neurological disorder or severe developmental disability of childhood.  Those affected exhibit severe impairments in reciprocal social interaction and communication, and a preference for repetitive, stereotyped behaviours.

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