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: Biochemistry
SCD is caused by a recessive, single-nucleotide mutation in the beta globin gene of Hgb. All of the following are TRUE about Sickle cell disease, EXCEPT: 
Select and explain. 
A. Single nucleotide change results in change of Glutamine to Valine, B. Sticky patch is generated as a result of replacement of a non polar residue with a polar residue, C. HbS confers resistance against malaria in heterozygotes, D. RFLP results from a single base change
B: Sticky patch is generated as a result of replacement of a non polar residue with a polar residue
Answer: B: Sticky patch is generated as a result of replacement of a non polar residue with a polar residue 
Explanation: When the sickle Hgb unloads its O2, the normal conformational change exposes the valine at position 6 to the surface creating a "hydrophobic (sticky) patch". The hydrophobic patch on one deoxygenated Hgb molecule can interact with the hydrophobic patch on a second Hgb molecule, creating stiff Hgb polymers. These internal polymers cause the RBC to stiffen and adopt abnormal shapes, including a crescent or "sickle" shape that gives the disease its name. Ref: Poeus M., Mantanona T. (2012). Chapter 14. Blood. In L.W. Janson, M.E. Tischler (Eds), The Big Picture: Medical Biochemistry.