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
In which of the following conditions splenctomy is not useful? 
Select and explain. 
A. Herediatary spherocytosis, B. Porphyria, C. Thalassemia, D. Sickle cell disease with large spleen
B: Porphyria
Answer: B: Porphyria 
Explanation: None