FOP Awareness Day, observed worldwide every April 23, aims to educate the public about fibrodysplasia ossificans progressiva (FOP), a rare congenital disorder characterized by the gradual ossification of muscles, ligaments, and tendons, leading to immobility. The date commemorates the anniversary of the discovery of the gene responsible for FOP. The disease, also known as Münchmeyer’s disease or stone man disease, affects fewer than 1,000 confirmed cases globally and is often marked by deformed big toes in newborns. Patients experience flare-ups of painful swellings as new bone growth occurs, which can be triggered by trauma. As of 2025, the only approved treatment is palovarotene, which inhibits abnormal bone growth. Individuals can participate in FOP Awareness Day by learning about the disease, sharing information, donating to relevant organizations, and using the hashtag #FOPAwarenessDay on social media.