A rare condition marked by a sudden and profound loss of skills is biologically distinct from other forms of autism.

Children missing a stretch of DNA on chromosome 16 show worsening motor and social skills in the first eight years of life; those with an extra copy of the region do not show this decline.

Children with autism inherit a greater burden of common genetic variants associated with autism than would be expected by chance. These variants combine with rare, spontaneous mutations to boost autism risk.

Between the ages of 2 and 8, intelligence increases in half of children with autism. In some of these children, intellectual disability gives way to average intelligence.

A massive new analysis drops the ratio of boys to girls who qualify for an autism diagnosis to about 3-to-1.

A picture-based test is a fast and flexible way to assess intelligence in large studies of people with autism.

Girls who show severe emotional or behavioral problems are more likely to be diagnosed with autism than those who do not.

A combination of multiple diagnostic tests may gauge the extent to which adults with autism attempt to blend in.