at San Francisco, California and other locations
study started
estimated completion
Principal Investigator
by Anthony Portale
Photo of Anthony Portale
Anthony Portale



The objectives of this observational study are to characterize XLH disease presentation and progression and to assess long-term effectiveness and safety of burosumab.

Official Title

X-linked Hypophosphatemia Disease Monitoring Program (XLH-DMP)


The XLH-DMP is a global, prospective, multicenter, longitudinal, long-term outcomes program for subjects on or off any treatment designed to characterize XLH disease presentation and progression, assess long-term safety and effectiveness of burosumab, as well as prospectively investigate longitudinal change over time across biomarker(s), clinical assessments, and patient/caregiver-reported outcome measures in a representative population. The XLH-DMP will collect demographic, biochemical, physiologic, disease severity, and progression data in patients taking burosumab and those not taking burosumab. In this DMP, patients will only have access to burosumab through authorized prescribed use. The Sponsor will not provide any treatments as part of the DMP.


X-linked Hypophosphatemia Hypophosphatemic Rickets Fibroblast growth factor 23 (FGF23) KRN23 XLH Hypophosphatemia Familial Hypophosphatemic Rickets FGF23 Crysvita Rickets Rickets, Hypophosphatemic No intervention Not from Prior Burosumab Clinical Trial


You can join if…

  • Willing and able to provide informed consent or, in the case of patients under the age of 18 years (or 16 years, depending on the region), provide assent (if required) and informed consent by a legally authorized representative after the nature of the study has been explained, and prior to any research-related procedures.
  • Clinical diagnosis of XLH based on family history, OR confirmed PHEX mutation, OR biochemical profile consistent with XLH.
  • Willing and able to comply with the study visit schedule and study procedures.

You CAN'T join if...

  • Concurrent enrollment in an Ultragenyx-sponsored clinical trial is NOT permitted.
  • Serious medical or psychiatric comorbidity.
  • Less than one year of life expectancy.


  • University of California San Francisco in progress, not accepting new patients
    San Francisco California 94158 United States
  • Children's Hospital Los Angeles accepting new patients
    Los Angeles California 90027 United States

Lead Scientist at UCSF

  • Anthony Portale
    Professor, Pediatrics. Authored (or co-authored) 92 research publications.


accepting new patients
Start Date
Completion Date
Ultragenyx Pharmaceutical Inc
Study Type
Last Updated