Many different types of mutations can occur within the body. Sickle cell anemia is a disease that occurs when a mutation in a base pair of the hemoglobin beta gene causes a single replacement of the amino acid glutamic acid by the amino acid valine. As a result of this mutation, the individual’s blood cells take on a sickle shape under certain conditions and form clusters that can block blood vessels and cause organ damage. Which type of mutation causes sickle cell anemia?