Autism is characterised by-

Autism spectrum disorder (ASD) was previously known as Pervasive Developmental disorders, a phenotypically heterogenous group of neurodevelopmental syndromes, with a polygenic heritability. ASD was conceptualised as five discrete disorders, including autistic disorder, Asperger's syndrome, Childhood Disintegrative Disorder, rett's syndrome and Pervasive developmental disorder not otherwise specified. Current understanding on Etiology of Autism includes- Genetics, Biomarkers (abnormal signaling in 5HT system, mTOR linked synaptice plasticity mechanisma, alterations of GABA inhibitory system), Immunological factors, Prenatal & Perinatal factors, Comorbid neurological disorders and Psychosocial theories. Ref: Synopsis of Psychiatry, 11e, pg 1152 to 1155.