A study of more than 5 million people reveals the onset and prevalence of nine diagnoses that often accompany autism.

Autism may be just as common among children missing a segment of chromosome 16 as it is in those with an extra copy.

An analysis of DNA from more than 20,000 people with autism identifies 12 regions in the genome that harbor inherited risk factors for the condition.

Autism and schizophrenia co-occur significantly more often than would be expected by chance, according to an analysis of nearly 2 million people.

Autism is more heritable than anorexia, alcohol dependence, depression and obsessive-compulsive disorder, according to an analysis of data from nearly 4.5 million people.

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.