Asfotase alfa (STRENSIQ®; Alexion, AstraZeneca Rare Disease), the first recombinant TNSALP enzyme replacement therapy (ERT) for treating HPP,11,12 was developed to address the underlying cause of HPP by supplementing the deficient enzyme, thus correcting mineralization defects of the skeleton and improving bone health and other systemic manifestations in patients with HPP. This evidence concerns the gene ALPL and hypophosphatasia.