Hypophosphatasia (hī-pō-ˌfäs-fə-ˈtā-zh(ē-)ə) or HPP is an inherited (genetic) metabolic disorder. People with this condition have low levels of the enzyme alkaline phosphatase (ALP), which often affects the development of bones and teeth. However, signs and symptoms vary widely, with mild cases causing only dental abnormalities while more severe types may have life-threatening consequences. Without adequate ALP, bones may become weak or soft, causing skeletal deformities, fractures, premature tooth loss, and pain, among other symptoms.