This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Child Psychiatry, Subject name: Psychiatry
All of the following are classified under Pervasive Developmental Disorders except? 
Select and explain. 
A. Asperger Syndrome, B. Childhood Disintegrative Disorder, C. Down Syndrome, D. Heller's syndrome
C: Down Syndrome
Answer: C: Down Syndrome 
Explanation: Ans. C. Down SyndromePervasive developmental disorder includes:* Autistic disorder* Asperger's disorder* Childhood disintegrative disorder,* Rett syndrome* Pervasive developmental disorder not otherwise specified.