Genetic studies in children with intellectual disability and autistic spectrum of disorders.

Autism is one of the five disorders that falls under the umbrella of Pervasive Developmental Disorders (PDD) or Autism Spectrum Disorder (ASD), a category of neurological disorders characterized by "severe and pervasive impairment in several areas of development." ASD is characterized by varying degrees of impairment in communication skills, social interaction and restricted, repetitive stereotyped patterns of behavior. The five disorders under PDD are autistic disorder, Asperger's disorder, childhood disintegrative disorder, Rett's disorder and PDD-not otherwise specified. ASD can often be reliably detected by the age of 3 years and, in some cases, as early as 18 months. The appearance of any warning signs of ASD is reason to have the child evaluated by a professional specializing in these disorders.