This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
All of the following are causes of pancytopenia with cellular bone marrow except: 
Select and explain. 
A. Paroxysomal noctural hemoglobinuria, B. Dyskeratosis congenita, C. Megaloblastic anemia, D. Hairy cell leukemia
B: Dyskeratosis congenita
Answer: B: Dyskeratosis congenita 
Explanation: Answer is B (Dyskeratosis congenita) Dyskeratosis congenita is associated with Pancytopenia and a hypocellular marrow.