This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hemoglobinopathies: Sickle cell anemia, Subject name: Pathology
Which of the following is true about sickle cells? 
Select and explain. 
A. Sickling occurs equally in both heterozygous and homozygous variants, B. Fetal hemoglobin facilitates sickling, C. Sickling is reversible with oxygenation, D. Sickling is associated with reduced MCHC
C: Sickling is reversible with oxygenation
Answer: C: Sickling is reversible with oxygenation 
Explanation: - Sickle cell disease is a common familial hemolytic anemia caused by a point mutation in b-globin in which glutamic acid is replaced by valine at 6th position. - It promotes the polymerization of deoxygenated hemoglobin, leading to red cell distoion, hemolytic anemia, microvascular obstruction, and ischemic tissue damage. - This sickling is reversible with oxygenation. - Sickling is severe in homozygous state than heterozygous state. - HbS facilitates sickling, not HbF - Dehydration & deoxygenation facilitates sickling