Explanation:

caused by a change in a single base pair of DNA

A group of disorders that cause red blood cells to become misshapen and break down.
With sickle cell disease, an inherited group of disorders, red blood cells contort into a sickle shape. The cells die early, leaving a shortage of healthy red blood cells (sickle cell anaemia) and can block blood flow causing pain (sickle cell crisis).
Infections, pain and fatigue are symptoms of sickle cell disease.
Treatments include medication, blood transfusions and rarely a bone-marrow transplant.