Sickle-cell anaemia is a hereditary blood disorder that affects the shape and function of red blood cells. It is also known by several synonyms, including sickle-cell disease, sickle-cell haemoglobinopathy, and sickle-cell trait. The condition is caused by a mutation in the HBB gene, which affects the production of haemoglobin in red blood cells. People with sickle-cell anaemia have crescent-shaped red blood cells that can block blood vessels and cause pain, organ damage, and an increased risk of infections. There is currently no cure for sickle-cell anaemia, but treatments such as hydroxyurea, blood transfusions, and bone marrow transplants can help manage the symptoms and improve quality of life.