Non-interventional Substudy of ALX-HPP-502 to Assess Natural History of Patients With Juvenile-onset HPP Who Served as Historical Controls in ENB-006-09

A Single-Center, Non-interventional Substudy of ALX-HPP-502 to Assess Functional Natural History Data of Patients With Juvenile Historical Controls in ENB-006-09

The purpose of this study is to characterize the natural history of HPP in patients with Juvenile-onset HPP who served as historical controls in ENB-006-09.

Hypophosphatasia (HPP) is a life-threatening, genetic, and ultra-rare metabolic disease characterized by defective bone mineralization and impaired phosphate and calcium regulation that can lead to progressive damage to multiple vital organs, including destruction and deformity of bones, profound muscle weakness, seizures, impaired renal function, and respiratory failure. There are no approved disease-modifying treatments for patients with this disease. There is also limited data available on the natural course of this disease over time, particularly in patients with the juvenile-onset form.

Inclusion Criteria:

• Documented informed consent/assent prior to video collection and data abstraction.
• Documented informed consent/assent in Study ALX-HPP-502.
• Patients with juvenile-onset HPP and was selected as a historical-control for Study ENB-006-09.
• Patients with at least 2 videos of basic mobility that were recorded at 2 different clinic visits when the patient was ≥5 to ≤15 ye

Exclusion Criteria:

• There are no exclusion criteria for this study