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
[{'content': 'Which of the following is not seen on hemoglobin electrophoresis in sickle cell anemia \nSelect and explain. \nA. HbA, B. HbA2, C. HbF, D. HbS', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref Harrison 19 th ed pg 634 sickle cell syndromes are caused by a mutation in the b-globin gene that changes the sixth amino acid from glutamic acid to valine. HbS (a2 b2 6 Glu-Val) polymerizes reversibly when deoxygenated . No beta chains and therfther no HbA', 'role': 'assistant'}]