Final Answer:
The specific Rare Pervasive Developmental Disorders dropped from DSM-5 include Childhood Disintegrative Disorder (CDD) and Rett Syndrome.
Step-by-step explanation:
The DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) made changes to the classification of pervasive developmental disorders. Childhood Disintegrative Disorder (CDD), previously considered a separate diagnosis characterized by late-onset developmental regression, and Rett Syndrome, a disorder primarily affecting females and involving neurological and developmental abnormalities, were both removed as distinct categories. Instead, these disorders are now subsumed under the broader umbrella of Autism Spectrum Disorder (ASD) in the DSM-5. The revision aimed to provide a more comprehensive and inclusive approach to understanding the diverse presentations within the spectrum of pervasive developmental disorders.
In summary, Childhood Disintegrative Disorder (CDD) and Rett Syndrome were the Rare Pervasive Developmental Disorders dropped from DSM-5.