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: Pathology
Which of the following causes hemolytic anemia -a) Hereditary spherocytosisb) Infectionc)  Iron deficiencyd) Sickle cell anemiae) Copper deficiency 
Select and explain. 
A. abd, B. bcd, C. abc, D. ab
A: abd
Answer: A: abd 
Explanation: Hemolytic anemia may be of two types.

 Intracorpuuscular

Underlying cause of hemolysis is intrinsic to RBC, e.g.,

Defect in membrane cytoskeleton → Hereditary spherocytosis
Defect in red cell enzyme → G6PD deficiency.
Disorder of hemoglobin synthesis 


Deficient globin synthesis →Thalassemia
Structurally abnormal globin → Sickle cell anaemia.
	(hemoglobinopathies)


Membrane defect → Paroxysmal nocturnal hemoglobinuria

                    2. Extracorpuscular
Underlying cause of hemolysis is extrinsic, ie., not within RBC, e.g., : -

Immunohemolytic anemia
Microangiopathic hemolytic anemia → (i) TTP,  (ii) HUS,  (iii) DIC
Infection → Malaria
Mechanical trauma to RBC → rosthetic valve.
Hyperspienism