Girl gap: Diagnostic tests may overlook some autistic girls but can measure traits accurately in those they identify. (mjrodafotografia / Getty Images)

A study from University of California, San Francisco finds that three major tests used to diagnose autism are as effective at recognizing traits like repetitive behavior and social difficulty in girls as they are in boys. Researchers had speculated that one cause of the 4:1 ratio of autism in boys to autism in girls might be that the diagnostic tests were not as effective at spotting autism-linked traits in girls.