Fragile X syndrome is a leading genetic cause of autism. People who have either condition often share certain traits, such as difficulties in social situations.

Genetic variants across the genome contribute to about 8 percent of the risk for certain developmental conditions — much more than previously thought.

More than half of people on the spectrum have four to five other conditions. Which conditions, and how and when they appear, varies from one autistic person to the next.

Over the past year, HNRNPU, a gene well known for its link to epilepsy, has emerged as a new autism candidate.

Children born to women who had diabetes or high blood pressure while pregnant may be at an increased risk of autism.

About 10 percent of people with a large mutation in chromosome 22 have autism, attention deficit hyperactivity disorder or intellectual disability.

Autism and intelligence share genetic variants, researchers grow Neanderthal mini-brains and see overlap with autism, and maternal diabetes is an autism risk factor.

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.