Answer:
The reason they have a sickled shape is that the underlying gene has the wrong instructions. These misshapen blood cells get clogged in vessels and don't have the life expectancy of normal blood cells. A person with sickle cell disease will experience fatigue (feeling tired) and have episodes of extreme pain, called a pain crisis. Sickled blood cells that block vessels in the brain can even cause a stroke.
I tried, hope this helps :)
