1. All of the following:
   • apparently normal prenatal and perinatal development
   • apparently normal psychomotor development through the first 5 months after birth
2. 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

Childhood Disintegrative Disorder

1. Apparently normal development for at least the first 2 years after birth as manifested by the presence of age-appropriate verbal and non verbal communication, social relationships, play, and adaptive behaviour
2. Clinically significant loss of previously acquired skills (before age 10 years) in at least two of the following areas:
   1. expressive or receptive language
   2. social skills or adaptive behaviour
   3. bowel or bladder control
   4. play
   5. motor skills
3. Abnormalities of functioning in at least two of the following areas:
   • qualitative impairment in social interaction (e.g., impairment in nonverbal behaviours, failure to develop peer relationships, lack of social or emotional reciprocity)
   • qualitative impairments in communication (e.g., delay or' lack of spoken language, inability to initiate or sustain a conversation, stereotyped and repetitive use of language, lack of varied make-believe play)
   • restricted, repetitive, and stereotyped patterns of behaviour, interests, and activities, including motor stereotypes and mannerisms
4. The disturbance is not better accounted for by another specific Pervasive Developmental Disorder or by Schizophrenia