Your browser does not support javascript:   Search for gard hereSearch for news-and-events here.


Genetic and Rare Diseases Information Center (GARD)

Print friendly version

Autism spectrum disorders


* Not a rare disease
Other Names for this Disease
  • ASD
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.


What are autism spectrum disorders (ASD)?

What causes autism spectrum disorders (ASD)?

Is genetic testing available for autism spectrum disorders (ASD)?

What are autism spectrum disorders (ASD)?

Autism spectrum disorders (ASD) are a group of developmental conditions characterized by social impairments, communication difficulties, and restricted, repetitive, and stereotyped patterns of behavior. Autistic disorder, sometimes called autism or classical ASD, is the most severe form of ASD, while other conditions along the spectrum include a milder form known as Asperger syndrome as well as childhood disintegrative disorder and pervasive developmental disorder not otherwise specified (PDD-NOS). Although ASD varies significantly in features and severity, it occurs worldwide and affects every age group.[1] Experts estimate that 1 out of 110 children will have an ASD.  Males are more likely to have an ASD than females.[2]
Last updated: 10/19/2011

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.[3]

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.[4]

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.[4]
Last updated: 10/19/2011

Is genetic testing available for autism spectrum disorders (ASD)?

Genetic testing can determine the cause of some cases of ASD. Currently, a genetic cause can be identified in 20% to 25% of children with ASD. The cause of ASD in the remaining 75% to 80% remains unknown. Genetic testing can help determine if a person has ASD caused by a chromosome abnormality or a single-gene disorder. Large chromosome abnormalities have been seen in about 5% of those with ASD; smaller deletions or duplications of genetic material has been found in about 10-20%; single gene disorders have been found in about 5% of those with ASD. Despite intensive research, no specific gene has been solely associated with ASD.[4]

GeneTests lists the names of laboratories that are performing genetic testing for ASD. To view the contact information for the clinical laboratories conducting testing, click here

Please note:  Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional. 
Last updated: 10/19/2011

  1. Autism Fact Sheet. National Institute of Neurological Disorders and Stroke. September 2011; Accessed 10/19/2011.
  2. About Autism. Autism Society of America. Accessed 10/19/2011.
  3. Causes. Autism Society of America. Accessed 10/19/2011.
  4. Miles JH et al.. Autism Spectrum Disorders. GeneReviews. April 2010; Accessed 10/19/2011.