2–6 per 10,000. M>F.
1 A, 1 B, 1 C.
- Impaired reciprocal social interaction (A symptoms)
- No attempt at friendship with peers, or lacks social conventions
- Abnormal play (uses play mates as furniture)
- Unaware of the existence or feelings of others
- Impaired imagination (B symptoms)
- No interest in stories
- Avoids mutual gaze
- Stiffens when held
- Does not act out adult roles
- Poor range of activities and interests (C symptoms)
- Limited range of interests
- Stereotyped movements
- Distress over minor changes
- Asperger's syndrome (normal intelligence, no delay in language acquisition)
- Rett's syndrome (females only, very rare, normal development until age 2)
There is no association with Down syndrome or cerebral palsy.
25–30% associated with epilepsy
- Fragile X syndrome
- Tuberous sclerosis
- hypomelanosis of Ito