This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: miscellaneous, Subject name: Biochemistry
[{'content': 'Sickling in &;HbS&; disease is primarily caused by \nSelect and explain. \nA. Decreased solubility, B. Decreased stability, C. Altered function, D. Altered O2 binding capacity', 'role': 'user'}, {'content': 'Answer: A \nExplanation: sickle-cell disease, which is caused by mutation of a single base out of the 3 x 109 in the genome, a T-to-A DNA substitution, which in turn results in an A-to-U change in the mRNA corresponding to the sixth codon of the b-globin gene. The altered codon specifies a different amino acid (valine rather than glutamic acid), and this causes a structural abnormality of the b-globin molecule leading to haemoglobin aggregation and red blood cell "sickling.".When HbS is deoxygenated, it undergoes a pronounced decrease in solubility', 'role': 'assistant'}]