This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Molecular Genetics, Subject name: Biochemistry
Sickle cell anemia is the clinical manifestation of homozygous genes for an abnormal hemoglobin molecule. The event responsible for the mutation in the B chain is: 
Select and explain. 
A. Insertion, B. Deletion, C. Nondisjunction, D. Point mutation
D: Point mutation
Answer: D: Point mutation 
Explanation: Ans. D. Point mutationThe mutation in HbS is an example ofPoint mutationPartially acceptable mis-sense mutationTransversionBase substitution.Nonconservative mutation