Autism spectrum disorder (ASD) is a condition that affects the development of social and communication skills. It includes features of four conditions which were once thought to be separate syndromes – autistic disorder, Asperger syndrome, childhood disintegrative disorder, and pervasive developmental disorder. Signs and symptoms often become apparent in the first 2-3 years of life and vary significantly from person to person. Common symptoms shared by people with ASD include restrictive and repetitive behaviors, social impairment and communication difficulties. The underlying cause of ASD is generally unknown and it is likely that a variety of factors contribute to the development of the condition. ASD appears to run in some families, suggesting that genetics may play a role in some cases. Although there is no cure for ASD, treatment is available that significantly improves the long-term outlook for affected people. Treatment often includes a combination of techniques such as medications, occupational therapy, speech therapy and physical therapy.