DSM IV-R Diagnostic Criteria for 299.80 Rett's Disorder

• All of the following:

1. apparently normal prenatal and perinatal development
2. apparently normal psychomotor development through the first 5 months after birth
3. normal head circumference at birth

• Onset of all of the following after the period of normal development:

1. deceleration of head growth between ages 5 and 48 months
2. loss of previously acquired purposeful hand skills between 5 and 30 months with the subsequent development of stereotyped hand movements (e.g., hand-wringing or hand washing)
3. loss of social engagement early in the course ( although often social interaction develops later)
4. appearance of poorly coordinated gait or trunk movements
5. severely impaired expressive and receptive language development with severe psychomotor retardation