[Autism spectrum disorder : ethiopathogenesis and benefits of early diagnosis].

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that manifests in altered or reduced social behaviours, social communication disorders, and repetitive behaviours and/or restricted interests. The etiology of ASD is complex and multifactorial. The etiopathogenesis of the disorder is multiple, including brain abnormalities, visual contact and early interaction disorders. These signs are often the focus of parental concerns. In addition, since ASD is neurodevelopmental, all signs are not always present simultaneously. Indeed, they appear progressively, until the age of 3 years, at which the diagnosis can usually be made. Nevertheless, in more complex cases, this diagnosis may be considered later. The first signs of ASD (before 24 months) will be addressed because they are crucial for an early diagnosis. Their knowledge allows the establishment of a follow-up as well as its quick specific care. Indeed, by acting during a developmental period when brain plasticity is high, early intervention allows to modify the evolution of symptoms, and later on to limit secondary handicaps.