It found that when a number of genetic disorders occur together, they account for up to 8 percent of Autism cases. The studies also found it may take a larger and more devastating genetic abnormality to cause autism in girls.
The findings reinforce the theory that autism is not caused by one or two major genetic defects, but, instead, by many small variations.
The findings are in the journal "Neuron". The Centers For Disease Control and Prevention says one in 110 American children are born with autism.