Similarly, children with hypophosphatasia (HPP)—a rare genetic disorder caused by deficient tissue-nonspecific alkaline phosphatase (TNSALP)—may benefit from enzyme replacement therapy with asfotase alfa, a recombinant form of ALP.240 By hydrolyzing inorganic pyrophosphate (PPi), a natural inhibitor of mineralization, asfotase alfa restores proper bone mineral deposition, promoting improved healing of fractures and pseudofractures in patients with HPP.241. The gene discussed is ALPL; the disease is hypophosphatasia.