Genomics and Health

Autism and Family History

Autism is one of a group of disorders known as autism spectrum disorders (ASDs). ASDs include autistic disorder, pervasive developmental disorder – not otherwise specified (PDD-NOS, including atypical autism), and Asperger syndrome. These conditions all have some of the same symptoms, but they differ in terms of when the symptoms start, how severe they are, and the exact nature of the symptoms.

People at risk

ASDs occur in all racial, ethnic, and socioeconomic groups and are five times more likely to occur in boys than in girls. CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network released data in 2012, indicating that about one in 88 eight-year old children in multiple areas of the United States have ASDs.

Genetics and family history

For most people with ASDs, the cause is not known. Scientists believe that both genes and the environment play a role in ASDs. Family studies have provided evidence for a genetic contribution to autism. Among identical twins, if one child has autism, the other will be affected about 60-96% of the time. The risk decreases to about 0-24% for non-identical twins. In addition, parents who have a child with ASD have a 2%-19% chance of having a second child who is also affected.
To read more about other suspected causes of ASDs, please visit the Autism Spectrum Disorders Overview web page.

Activities on ASDs

CDC conducts and funds research studies and monitoring activities to better understand and track ASDs in the United States. These research studies examine a number of potential risk factors for ASDs, such as infection and immune function, and genes that are related to these factors. CDC also conducts educational programs with healthcare providers and the public to help detect symptoms of ASDs early. To read more about these activities, please visit the CDC Activities web page.
The U.S. National Institutes of Health

and other agencies help to support the Autism Genome Project Consortium

, the largest search for autism-related genes to date. The consortium is pursuing studies to identify specific genes and gene variants that contribute to susceptibility to autism.