World HPP Day is observed worldwide every October 30 to promote awareness of hypophosphatasia, a rare genetic disorder that affects bone and dental health. The day aims to improve diagnosis rates and access to care for individuals with this condition, which can range in severity from mild dental issues to severe complications, including respiratory failure and early death. Hypophosphatasia is caused by mutations in the ALPL gene, leading to a deficiency of the enzyme tissue-nonspecific alkaline phosphatase, essential for proper bone and teeth mineralization. The disorder has five types, each characterized by different symptoms and age of onset. Individuals can participate in World HPP Day by learning about the disease, sharing information, donating to relevant organizations, and using the hashtag #WorldHPPDay on social media.