A Scottish scientist is part of a team which has uncovered the first genetic clues to autism in a breakthrough equivalent to the one that revolutionised the understanding and treatment of cancer 30 years ago.

A Scottish scientist is part of a team which has uncovered the first genetic clues to autism in a breakthrough equivalent to the one that revolutionised the understanding and treatment of cancer 30 years ago.

Three major studies have, for the first time, pinpointed genetic mechanisms underlying autistic disorders, including ones which are common.

One of the studies at the Centre for Applied Genomics at The Children's Hospital of Philadelphia found a common genetic variant that may account for as many as 15 per cent of cases of autism.

Scot Dr Struan Grant, associate director of the centre and co-author of both studies, said the research was a major breakthrough. "Autism is one of the diseases that has eluded geneticists for some time, which is surprising as there is a huge genetic element to autism," he said yesterday. "There have been no major breakthroughs until now."

Autism affects one in 100 people in the UK and leaves sufferers with difficulty understanding facial expressions or tone of voice and body language. A complex genetic jigsaw is believed to be responsible for the condition but identifying the pieces has proved difficult.

The two American studies, which involved screening the DNA of hundreds of volunteers, were reported yesterday in the journal Nature. A third study conducted by British scientists at Oxford University appears in the journal Molecular Psychiatry.

Part of the new research involved looking at the activity of a gene in the foetal brain. Scientists found it was most active in regions of the brain that support language, speech and social behaviour.