Sickle cell anemia is a disease in which red blood cells become irregularly shaped. The disease is caused by the presence of an incorrect amino acid in a certain protein. Is the sickle cell mutation beneficial, harmful, or neutral to humans?

It is harmful to humans.

Explanation:

Firstly, sickles are crescent-shaped blood cells that stick together often, blocking small blood vessels; this leads to very painful attempts to breathe. Since they can block the blood vessels, strokes are a frequent danger.