Sickle cell disease—the subject of a new Seminar in The Lancet—is one of the most prevalent and fastest-growing genetic disorders worldwide. Although its true prevalence is difficult to determine owing to the absence of screening in much of the world, the Global Burden of Diseases, Injuries, and Risk Factors Study estimates that nearly 8 million people are living with sickle cell disease. Deaths from sickle cell disease rose 18·4% between 2000 and 2023, from 45 600 to 54 000. Sub-Saharan Africa is home to three-quarters of infants born with the disease, where it causes more than one in 20 deaths in children younger than 5 years; most children affected do not live into adulthood. Life expectancy is also curtailed for people with sickle cell disease in high-income countries, with multiorgan complications and complex needs common in adult patients. Yet, the global standard of care for sickle cell disease is not commensurate with these stark realities.