Genes that make you smart may also be cause of autism

THE same genes that cause higher intelligence can also trigger autism.

A study of more than 5000 people found that the genes that are linked with exceptional brain power were also associated with the disorder.

The Yale University authors said the findings might explain why autism had not been eliminated by natural selection. Genes that had a negative effect on reproductive success normally died out.

The researchers said a variety of genes known to have effects, including boosting brain growth were beneficial in most cases, and that was why they continued to be passed on. But the downside was that the same genes increased the chances of autism.

Autism – more properly known as autism spectrum disorders – includes Asperger’s disease.

It has long been known that some people with autism have superior abilities in areas such as mathematics and science. It affects four to five times as many males as females. Those with the condition can also have difficulties with understanding language and the rules of social inter-action, as well as understanding emotion.

They concluded that the genetic variants found in people with autistic disorder were present at a much higher rate than would be expected by chance. This showed that the genes have a “signature for positive selection”.

The authors, writing in PLOS Genetics, said previous research had found many overlaps between autism and having a high IQ. But this was the first time that it had been shown that the genes linked to higher IQ and autism are being positively selected in evolution.–