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Genetic and Rare Diseases Information Center (GARD)

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Autism spectrum disorders


* Not a rare disease
Other Names for this Disease
  • ASD
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What causes autism spectrum disorders (ASD)?

There is no known single cause of autism spectrum disorders, but it is generally accepted that ASD is caused by abnormalities in brain structure or function. Brain scans often show differences in the shape and structure of the brain in children with ASD versus children without ASD. Researchers are investigating a number of theories, including the link between heredity, genetics, and medical problems. In many families, there appears to be a pattern of autism or related disabilities, further supporting a genetic basis to the disorder. While no one gene has been identified as causing ASD, researchers are searching for genetic material that children with ASD may have inherited. It also appears that some children are born with a susceptibility to ASD, but researchers have not yet identified a single "trigger" that causes autism to develop.[1]

Currently a genetic cause can be identified in 20% to 25% of children with ASD. The cause of autism in the remaining 75% to 80% remains unknown.[2]

A small number of cases can be traced to specific exposures during pregnancy. However, it remains unclear whether those who develop autism after such an exposure are also genetically predisposed to develop ASD. The search for other environmental causes of ASD has centered primarily on childhood immunizations given around the time that ASD is recognized; however, no scientific evidence for a relationship between vaccines and autism has been identified.[2]
Last updated: 10/19/2011

  1. Causes. Autism Society of America. Accessed 10/19/2011.
  2. Miles JH et al.. Autism Spectrum Disorders. GeneReviews. April 2010; Accessed 10/19/2011.