autism

autism A spectrum of neuropsychiatric disorders characterized by deficits in social interaction and communication and by unusual and repetitive behavior. Some, but not all, people with autism are nonverbal. Autism is normally diagnosed before age 6, and it may be diagnosed in infancy in some cases. The cause of autism is currently unknown, although it is believed to involve an inherited or acquired genetic defect involving multiple chromosomes, possibly including chromosomes 6, 15, 17, and/or the X chromosome. Autism is not caused by emotional trauma, as was once theorized. Autistic or autistic-like behavior may be caused by other neurological conditions—particularly the seizure disorder Landau-Kleffner syndrome—certain forms of encephalitis, and several genetic disorders, including Angelman syndrome and Rett syndrome. Also known as Kanner syndrome or infantile autism. See also Asperger syndrome; elective mutism; fragile X syndrome; Landau-Kleffner syndrome; Prader-Willi syndrome; Rett syndrome.