Hypophosphatasia is a rare inherited metabolic disorder due to inactivating mutations of the ALPL-Gene. Particularly among adult patients, clinical manifestation exhibits a broad range of signs and symptoms, most commonly associated with musculoskeletal disabilities and compromised quality of life. Enzyme replacement therapy with Asfotase alfa (AA) is available and approved for patients with pediatric onset of the disease.

This single-center observational cohort study aims at collecting clinical routine data regarding the course treatment, quality of life and physical performance in patients treated with Asfotase alfa in line with the label for pediatric-onset hypophosphatasia.

Inclusion Criteria:

• Age ≥ 18 years at the time of enrollment
• Clinical diagnosis of pediatric-onset HPP based on low ALP (age- and sex-adjusted) and/or genetic confirmation of ALPL mutation(s), and clinical symptoms consistent with HPP
• Participant currently receiving commercial asfotase alfa treatment for HPP at the Orthopedic Institute of the Julius-Maximilians-University Würzburg, as per standard of care
• Willingness to participate in the study
• Signed informed consent

Exclusion Criteria:

• Unwillingness / anticipated inability to attend further visits
• Off-label treatment with asfotase alfa
• Current participation in an Alexion Sponsored Trial
• Experimental drug/treatment

Study population consists of male and female HPP patients with pediatric-onset HPP currently being managed for the disease at the Orthopedic Institute of the Julius-Maximilians-University Würzburg, Germany and receiving commercial AA treatment as per the standard of care.