Sickle cell disease is a genetic disorder in humans that can cause severe symptoms, such as pain and anemia. It affects the shape of the red blood cells, due to an alteration in hemoglobin, the protein that carries oxygen and carbon dioxide. In this alteration, the (beta) units of hemoglobin have been modified, and now aggregate into a fiber, causing the cells to have the shape of a sickle.


Which of the following statements BEST describes how changes in DNA and a protein can affect their interactions and cause sickle cell disease?