Defintion

1. Rett Syndrome, Childhood Disintegrative Disorder, Pervasive Developmental Disorder – Not Otherwise Specified (PDD – NOS)

2. Defintion Rett syndrome is a distinct neurological condition that begins between 5 and 30 months of age following an apparently normal early infancy.

3. Features • The baby’s head growth slows, purposeful use of the hands is replaced with stereotypic hand movements (e.g., wringing and mouthing), • there is a gradual onset of unsteadiness and awkward gait, and • severe impairments in language and cognitive abilities ensue.

4. Continued… • Seizures are common. • Rett syndrome primarily affects girls. * Although it is on the ASD continuum, Rett’s syndrome is considered to be a distinct neurological condition. *

5. Childhood Disintegrative Disorder • Childhood disintegrative disorder shares behavioral characteristics with autistic disorder, but the condition does not begin until after age 2 and sometimes not until the child has reached age 10. • Medical complications are common, and the prognosis for significant improvement is usually very poor.

6. Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS). • Children who meet some, but not all of the qualitative or quantitative criteria for autistic disorder are often diagnosed as having pervasive developmental disorder—not otherwise specified (PDD-NOS). • All children with PDD-NOS have significant impairments in socialization with difficulties in either communication or restricted interests.

7. Continued… • The boundaries for PDD-NOS are not well defined, and children with socialization problems as the result of other conditions may be misdiagnosed.