In a study, the Swiss researchers collaborated with scientists from the University of Washington School of Medicine to analyze about 16,000 DNA samples and sequencing data sets from people with neurodevelopmental disorders, including autism spectrum disorders, and they also analyzed genetic data from almost 800 families affected by autism for the study, which was released online Feb. 27 in the American Journal of Human Genetics.

It turns out that girls tend not to develop autism when only mild genetic abnormalities exist, the researchers said. But when they are diagnosed with the disorder, they are more likely to have more extreme genetic mutations than boys who show the same symptoms. The study authors pointed out that autism affects four boys for every one girl. The ratio increases to seven-to-one when looking at high-functioning autism cases.