Abstract | Summary | Original Article

Mapping the genes for autism:
Canadian study part of a worldwide effort

Is autism a genetically inherited disorder? If so, which gene or genes are responsible?

More than 170 of the world’s leading genetic researchers, including about a dozen right here in Canada, are searching for the answers by going to the most likely source, families who have two or more children affected with the disorder.

More than 1,200 families from all over the world, including 200 families across Canada, are participating in this global research collaboration, the largest ever assembled to locate the genes associated with autism spectrum disorders. The Canadian study is funded by the Canadian Institutes for Health Research. The project involves collecting blood and DNA samples from parents and their children to track inheritance in families and to better understand the genetic-biochemical changes causing autism and Pervasive Developmental Disorder (PDD).

The Canadian study is being led by Peter Szatmari of the Offord Centre for Child Studies in Hamilton, Ontario, and Steve Scherer of The Hospital for Sick Children in Toronto. The group is looking for two types of genes: susceptibility genes, which are responsible for the inherited risk for autism; and modifier genes, which are not directly responsible for autism but which may have an effect on clinical expression and could help to shed light on why symptoms can vary so greatly from one individual to another.

Locating the genes will be no easy task. There are approximately 30,000 genes in the 23 chromosomes that make up the human genome. Roughly 4,000 of these genes are located in the brain. Autism is known as a complex disorder that is believed to involve many genes on several chromosomes.

Preliminary findings have zeroed in on Chromosome 7 as one hot spot for continued research. But while results are promising, there remains much work to be done. Researchers hope eventually to enable clinicians to biologically diagnose autism, allowing children to be diagnosed earlier than ever and leading to more effective treatments and better outcomes for them and their families. Knowing what causes autism may even allow us, one day, to prevent it.

Researchers involved in the Canadian study include:

Susan Bryson, PhD, Dalhousie University
Jeremy Goldberg, MD, McMaster University
Marshall Jones, PhD, The Pennsylvania State University, College of Medicine
Bill Mahoney, MD, McMaster University
Chantal Merette, PhD, Laval University
Roberta Palmour, MD, McGill University
Andrew Paterson, MD, University of Toronto
Wendy Roberts, MD, University of Toronto
Lawrence Tuff, PhD, McMaster University
John Vincent, PhD, University of Toronto
Lonnie Zwaigenbaum, MD, McMaster University.

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