Shirley Wang:

Why do boys get diagnosed with autism four times as often as girls?
New research, including some of the latest data from the International Society for Autism Research annual conference last week, addresses this question, one of the biggest mysteries in this field. A growing consensus is arguing that sex differences exist in genetic susceptibility, brain development and social learning in autism–and they are meaningful to our understanding of the disorder and how it will be treated.
Yale University researchers presented results showing that being female appears to provide genetic protection against autism. Meanwhile, scientists at Emory University showed in preliminary work that boys and girls with autism learn social information differently, which leads to divergent success in interactions with other people.