Rats with a mutation in CACNA1C, a gene linked to autism, make fewer happy squeaks while playing than controls do, and ignore other rats’ requests to play.

Mice with a mutation in a top autism gene may have altered levels of certain gut bacteria; feeding the mice one of these bacterial species eases some of their troubles.

The pupils of babies later diagnosed with autism shrink more in response to light than those of their typical peers.

Two new parent questionnaires could help clinicians identify autism in babies and in members of racial or ethnic minority groups.

People with mutations in SHANK3 have milder features than do those missing a chunk of DNA that includes the gene.

Girls with autism traits have fewer problems with social communication than boys do early on, but their skills worsen by adolescence.

Young people with autism have more psychiatric and medical conditions than do their typical peers or those with attention deficit hyperactivity disorder.

More boys than girls have autism; diagnostic biases and genetic factors may explain the skewed sex ratio.