Using Genetics to Unlock Autism's Mysteries

Neuroscience research profile: Dr. John Vincent 

Autism is a severe, complex developmental disorder that affects the way a person communicates and relates to others. It has a stronger genetic component than any other neuropsychiatric disorder. Though autism impacts hundreds of thousands of families around the world, little is known about its causes.

Through his work in the Neurogenetics section of CAMH’s Neuroscience Department, Dr. John Vincent is helping to unlock the mysteries of autism. “We are still at the understanding phase of autism,” says Dr. Vincent. But by remaining open to a range of experimental approaches, he hopes to discover whether one gene, several or many genes, environmental influences or a combination of these factors causes the disorder.

A recent study by Dr. Vincent and colleagues* provided further evidence to support the theory that a particular gene cluster—GABA receptor genes—might be involved in the origins of autism. They discovered that two brothers with autism both had an identical change to the same chromosome (chromosome 4p) within this cluster of genes. Analysis of this change—a large segment of the chromosome was inverted—suggests that this specific gene cluster may be relevant to the causes of autism. This finding is in line with a number of previous studies that have implicated a role for the neurotransmitter GABA (gamma-amino butyric acid) in autism.

Through an international collaboration, Dr. Vincent is also taking a different approach to understanding autism. In a preliminary study using large families with autism in Pakistan, Dr. Vincent and colleagues are treating autism as a single gene disorder.

They hope to learn from unique features of the population they are studying. In many families in Pakistan intra-family marriages are very common. This means that if there is a genetic abnormality, it gets passed on and stays in the family. As a consequence, rare recessive diseases (which occur only if both parents carry the relevant gene) can recur with great frequency within the family.

Dr. Vincent hopes that by studying this genetically unique population, his team will find enough evidence to identify a specific autism gene or genes, or to narrow down the region of investigation to a small part of one chromosome. They could then combine this family data with existing information from other lines of research to identify a new gene in a specific region.

Researchers still have many more questions than answers about autism. Dr. Vincent’s diverse approach is perhaps our best chance at understanding this complex disorder.

“In the years to come,” says Dr. Vincent, “we may find that the combined effect of a number of genes may cause autism. In other cases it may be caused by a single gene, which may be inherited recessively or may mutate randomly during genetic transmission. We just don’t know yet. To find the answers we must try new approaches—possibly combinations of approaches—and be open to new ideas.”

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