Sickle cell disease is a hereditary disorder that affects red blood cells, distorting their natural disc shape into a crescent moon or "sickle" shape. Normal red blood cells move freely through small vessels throughout the body to deliver oxygen. With sickle cell disease, the misshapen red blood cells become hard and sticky, making it difficult for them to move through blood vessels. They eventually block the flow and break apart. This process results in a number of problems including severe chronic pain, stroke, organ damage, spleen dysfunction, heart failure and even death.