Classic autism, also known as childhood autism, autistic disorder, (early) infantile autism, infantile psychosis, Kanner's autism, Kanner's syndrome, or (formerly) just autism, is a neurodevelopmental condition first described by Leo Kanner in 1943. It is characterized by atypical and impaired development in social interaction and communication as well as restricted, repetitive behaviors, activities, and interests. These symptoms first appear in early childhood and persist throughout life. It was last recognized as a diagnosis in the DSM-IV and ICD-10, and has been superseded by autism spectrum disorder in the DSM-5 (2013) and ICD-11 (2022). Globally, classic autism was estimated to affect 24.8 million people as of 2015. Autism is caused by a combination of genetic and environmental factors, with genetic factors thought to heavily predominate. Controversies surrounded other proposed environmental causes; for example, the vaccine hypothesis, which although disproved, continues to hold sway in certain communities. After DSM-5/ICD-11 the term "autism" has become more commonly used in reference to the autism spectrum more broadly.

Reference
Wiki: Autistic disorder