Abstract

Neurodevelopmental disorders include autism spectrum disorders (ASDs). Although the exact cause of ASD is unknown, a number of genetic and non-genetic risk factors have been identified that, either on their own or in combination, may contribute to the disorder’s onset. There are currently no diagnostic biomarkers, and the diagnosis of ASD is based on typical characteristics such as impaired social communication and interaction and repetitive behaviors. These behaviors have been suggested to be caused by a number of pathomechanisms, including synaptic defects and changes in brain development and function. The clinical phenotype and severity may also be altered by processes that occur outside the central nervous system. This chapter provides a synopsis of the clinical characteristics of ASD, draws attention to significant genetic and non-genetic risk factors for ASD, and introduces the most recent understanding of the pathological processes that take place both inside and outside the brain.