This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Anatomy
Megaloblastic anemia may be caused by all the following except 
Select and explain. 
A. Liver disease, B. Copper deficiency, C. Thiamine deficiency, D. Orotic aciduria
B: Copper deficiency
Answer: B: Copper deficiency 
Explanation: Ref Harrison 19 th ed pg 640 Table,;128-1 Causes of Megalobla stic Anemia Cobalamin deficiency or abnormalities of cobalamin metabolism Folate deficiency or abnormalities of folate metabolism Therapy with antifolate drugs (e.g., methotrexate) Independent of either cobalamin or folate deficiency and refractory to cobalamin and folate therapy: Some cases of acute myeloid leukemia, myelodysplasia Therapy with drugs interfering with synthesis of DNA (e.g., cytosine arabinoside, hydroxyurea, 6-mercaptopurine, azidothymidine ) Orotic aciduria (responds to uridine) Thiamine-responsive