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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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Which of the following can be a homologous substitution for valine in hemoglobin?
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The correct answer is  In Many examples of Point Mutations The classic example is 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 hemoglobin aggregation and red blood cell "sickling." Ref: Harper's Illustrated Biochemistry, 30E (2015) Pg no 460.