The essential feature of Rett’s Disorder is the development of multiple specific deficits following a period of normal functioning after birth. There is a loss of previously acquired purposeful hand skills before subsequent development of characteristic hand movement resembling hand wringing or hand washing. Interest in the social environment diminishes in the first few years after the onset of the disorder. There is also significant impairment in expressive and receptive language development with severe psychomotor retardation. (Page 71)
A. All of the following:
Apparently normal prenatal and prenatal development
Apparently normal psychomotor development through the first 5 months after birth
Normal head circumference at birth
B. Onset of all of the following after the period of normal development:
Deceleration of head growth between ages 5 and 48 months
Loss of previously acquired purposeful hand skills between ages 5 and 30 months with the subsequent development of stereotyped hand movements (e.g., hand-wringing or hand washing)
Loss of social engagement early in the course (although often social interaction develops later)
Appearance of poorly coordinated gait or trunk movements
Severely impaired expressive and receptive language development with severe psychomotor retardation