AUTISM is more prevalent in boys, but now, scientists say how the condition strikes girls, or doesn’t, may help reveal some of the disorder’s frustrating secrets. Autism is at least four times more common in boys, but scientists say many girls with autism have better social skills that allow them to mask the condition. Some girls also show no symptoms of autism even when they have the same genetic mutations seen in boys with the condition. It could be that autism is not the same in boys and girls as its causes are not known, but the gender effect is now a hot topic in autism research in the USA where at least one in 68 children are affected. Brain imaging suggests there may be an additional explanation for why many girls with autism have more subtle symptoms than boys as the brain regions involved in social behaviour that are normally affected are less severely impaired. Researchers at a medical school in New York also found girls have to have twice as many gene mutations to manifest with autism symptoms. Scientists have launched a project seeking to enrol hundreds of families with autistic sons but unaffected daughters in a bid to build a database that scientists can use to look for genetic clues and protective factors and learn more about autism. The condition can be difficult to determine and is diagnosed by observing behaviour, there is no blood test for it. All forms of autism are more common in boys and the average age at diagnosis is four.