London: Mutations in a parent`s sperm or egg cells may increase a child`s risk for autism, and fathers are more likely to pass these defects to their children than their mothers, researchers have claimed.
Three large-scale studies, published in journal Nature, have highlighted the importance of defects in the DNA of eggs and sperm to the development of autism, and one in seven cases of autism in families are caused this way.
One study by a team from the University of Washington showed sperm to be a much bigger culprit than eggs. For every four such genetic alterations, known as "de novo" mutations, traced back to sperm, there was just one that began life in an egg, it found.
For their study, the researchers analysed the DNA of children with autism and their parents in 209 families where the child was the only autistic person, as well as 50 unaffected siblings.
They found 248 "de novo" mutations, 60 of which they identified as the most likely to raise the risk of autism, the Daily Mail reported.
Pooling the results of the three studies revealed that three genes to be peppered by these de novo mutations.
The scientists said that it is likely that hundreds of genes are involved in autism and their study shows the picture to be even more complex than thought.
It is hoped that unravelling the genetics will speed up both the search for new treatments for the condition and the development of diagnostic tests.
Stephen Sanders, who led the project at Yale University, said: "With every new gene we discover, we learn more about potential treatments for patients with autism."
Autism, and related conditions like Asperger`s syndrome, affect more than one in 100 children in the UK alone. But with the causes unclear, current treatment consists of managing individual symptoms, such as hyperactivity.
The lead scientist on the third project, Mark Daly of Massachusetts General Hospital, said: "These results clearly demonstrate the potential of DNA sequencing technology to articulate specific risk factors for autism.
"We have only scratched the surface but, with continued collaborative efforts, these gene discoveries will point us towards the underlying biological roots of autism."
Kevin Mitchell, a Trinity College Dublin geneticist, said work such as this would allow the underlying cause of autism to be treated, rather than just the symptoms.