Autism spectrum disorder (ASD) is a relatively common developmental disability affecting 1 in every 68 children in the US. Boys are diagnosed with ASD about five times more often than girls. ASD is a behaviorally-defined condition with many known and unknown causes. Diagnosable genetic disorders are the most common known causes, and clinical genetic testing is recommended as part of the comprehensive medical evaluation of individuals with ASD. Autism spectrum disorder (ASD) affects a person’s behavior, communication, and social skills. It is referred to as a spectrum disorder because of variability in the severity of symptoms, particularly related to social interaction and communication. Individuals with ASD and their families often require support throughout the lifespan.