Signs & Symptoms

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.

Mice and people missing a copy of a chromosomal region called 16p11.2 show similar patterns of weak brain connections.

Boys with autism have smaller heads, are shorter and weigh less at birth than typical children do — but all that changes by age 3.

The brains of people with autism show a variety of structural differences from those of controls.

Exposing fertilized chicken eggs to valproic acid, an epilepsy drug, yields chicks with apparent social deficits.

Female mice may compensate for the loss of a piece of chromosome 16 better than male mice do.

Male monkeys that avoid touching, grooming or playing with others have low brain levels of the hormone vasopressin.