Professor David Skuse, of Britain’s Institute of Child Health, says a part of the brain that is key to reading expressions in people’s faces – and which is affected by the X chromosome – could give a new insight into the causes of the disease.
A small group of genes on the X chromosome regulate the brain’s “threat-detector” and might explain the high prevalence of autism among males, researchers have discovered.
Some people lacking these genes have problems recognising fear in another person’s face, a common trait in autism. They also have abnormal amygdalas – a brain area known as the “fear centre”.
Previous research suggests autism has a genetic basis, but so far, no single gene has been located that causes the disease in the general population. Autism is 10 times more prevalent among boys than girls, suggesting that a genetic factor may be sex-linked.
Because men only have one X-chromosome, they are more vulnerable to the effects of any deletions or anomalies of genes on this chromosome, and therefore more likely to suffer from autism.
Other than fear, people with autism often fail to recognise beliefs and intentions in others, and this has led to harsh publicity for men. “Because so many more men than women have autism, some have suggested in the past that autism is merely an extreme of normal male behaviour,” Skuse said.
“Ultimately, we aim to discover how [these genes] influence the development of the social brain,” said Skuse.