Harmful mutations in a gene called NAA15 may lead to autism, intellectual disability and delayed speech and motor function.

Mutations in certain genes contribute specifically to autism, and others only to developmental delay.

Mutations in a gene called ADNP lead to a syndrome that includes autism, intellectual disability and problems with the gut, eyesight, heart and brain.

Children with autism typically have four or five other conditions, such as attention deficit hyperactivity disorder, that can affect when they are diagnosed.

A single gene, OTUD7A, may account for most of the features seen in people missing a segment of chromosome 15 known as 15q13.3.

A semirural Colombian town called Ricaurte is home to the largest recorded genetic cluster of people with mutations linked to fragile X syndrome.

People with autism who are admitted to the hospital for self-injury tend to have low intelligence quotients and severe repetitive behaviors.