Why Autism is More Common in Boys

November 15th, 2010 | Sources: BurrillReport


Toronto-based scientists have found that boys with a specific DNA mutation on their X-chromosomes are at high risk of developing Autism Spectrum Disorder (ASD).

To reach these conclusions, John Vincent and colleagues at the Centre for Addiction and Mental Health compared the gene sequences of 2,000 people with ASD with a control group that had no behavioral or intellectual limitations.

The scientists found that about 1% of boys with ASD also had mutations in a gene known as PTCHD1, which is located on the X-chromosome. The scientists did not find these mutations in boys who were in the control group.

“We believe the PTCHD1 gene has a role in a neurobiological pathway that delivers information to cells during brain development–this mutation may disrupt crucial developmental processes, contributing to the onset of autism,” Vincent told BurrillReport. “Our discovery will facilitate early detection (and) increase the likelihood of successful interventions.”

ASD is a neurological condition associated with abnormal social interaction and communication, unusual behaviors, and frequently, diminished intelligence. It affects about one in 240 girls and one in 70 boys. The causes of ASD remain unknown, though scientists have long suspected that genetic factors play a role.

Boys inherit an X-chromosome from their mothers and a Y-chromosome from their fathers. If a boy’s lone X-chromosome lacks a normally functioning PTCHD1 gene, he is at risk for ASD or some other intellectual disability, the scientists explained. Girls inherit an X-chromosome from their mothers and fathers, so the effects of a PTCHD1 gene defect in one X-chromosome are masked by the normally functioning gene on the other X-chromosome. These girls will not develop ASD, but their male offspring are at risk.

The study appears in Science Translational Medicine. 



  1. Erica | 8/02/11

    I never thought that genetics can also explain how this syndrome develops. Thanks for this information. Looking forward for your future post.

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