Genes: Bits of DNA that carry instructions for "building" your body.
Chromosomes: Packages of DNA and genes in the cells of the body.
A great deal of evidence supports the idea that genes are one of the main causes of or a major contributor to ASD. More than 100 genes on different chromosomes may be involved in causing ASD, to different degrees.3,4
Many people with autism have slight changes, called mutations, in many of these genes. However, the link between genetic mutations and autism is complex:
- Most people with autism have different mutations and combinations of mutations. Not everyone with autism has changes in every gene that scientists have linked to ASD.
- Many people without autism or autism symptoms also have some of these genetic mutations that scientists have linked to autism.
This evidence means that different genetic mutations probably play different roles in ASD. For example, certain mutations or combinations of mutations might:
- Cause specific symptoms of ASD
- Control how mild or severe those symptoms are
- Increase susceptibility to autism. This means someone with one of these gene mutations is at greater risk for autism than someone without the mutation.