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
[{'content': 'Sickle cell trait patient do not have manifestations as that of Sickle cell disease, because? \nSelect and explain. \nA. 50% HbS is required for occurrence of sickling, B. HbA prevents sickling, C. 50% sickles, D. HbA prevents polymerazitation of Hbs', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., 50% Hbs is required for occurence of sickling Sickle cell disease occurs in following forms 1. Heterozygous state, i.e., sickle cell trait. 2. Homozygous state, i.e., sickle cell anemia. o The most impoant factor for sickling is the amount of HbS in the cell. o In sickle cell trait (heterozygous state), only about 40% of the hemoglobin is HbS, this is insufficient to produce sickling manifestations. o In homozygous state, almost all the hemoglobin in the red cell is HbS, therefore they undergo sickling.", 'role': 'assistant'}]