Sickle cell disease is an inherited blood disorder that affects hemoglobin, the protein that carries oxygen through the body. It is caused by a genetic mutation that affects the shape of red blood cells, making them stiff and sickle-shaped. This abnormal hemoglobin causes the red blood cells to become rigid, sticky, and misshapen, leading to a constant shortage of red blood cells. A person will be born with sickle cell disease only if they inherit two genes, one from each parent. If a person inherits only one gene, they are healthy and said to be a "carrier" of the disease.

The hemoglobin associated with sickle cell disease causes red blood cells to become rigid, sticky, and misshapen. This can lead to a variety of symptoms and complications, including anemia, chronic pain, swelling of hands and feet, unexplained numbness, severe headache, organ damage, leg ulcers, gallstones, and priapism. Sickle cells that block blood flow to organs deprive the affected organs of blood and oxygen, which can cause damage to the kidneys, liver, spleen, and other organs.

In summary, sickle cell disease is caused by a genetic mutation that affects the shape of red blood cells, making them stiff and sickle-shaped. This abnormal hemoglobin causes a constant shortage of red blood cells and can lead to a variety of symptoms and complications affecting multiple organs in the body.