Also known as X-linked hypophosphatemic rickets, familial hypophosphatemia, familial hypophosphatemic rickets, vitamin D-resistant rickets (VDRR), genetic rickets
What is it?
X-linked hypophosphatemia (XLH) is a rare, progressive, and lifelong disorder caused by low levels of phosphate in the bloodstream.1
What Causes It?
People with XLH produce too much of a protein called fibroblast growth factor 23 (FGF23). Too much FGF23 causes the kidneys to waste phosphate into the urine and results in chronically low levels of phosphate in the bloodstream, is also known as hypophosphatemia. Phosphate is essential for building bones and teeth.
What Are Some Common Symptoms?2
- Bone and joint pain
- Bowed legs and/or knock-knees
- Delayed growth
- Irregular head shape
- Muscle weakness
- Osteomalacia
- Short stature
- Tooth abscesses
How Many People Have It?
XLH is a rare disorder, occurring in anywhere from 1 in 20,000 to 1 in 25,000, people.2
Linglart A, Biosse‐Duplan M, Briot K, et al. Therapeutic management of hypophosphatemic rickets from infancy to adulthood. Endocr Connect. 2014;3(1):R13‐R30.
Beck-Nielsen SS, Brock-Jacobsen B, Gram J, Brixen K, Jensen TK. Incidence and prevalence of nutritional and hereditary rickets in southern Denmark. Eur J Endocrinol. 2009; 160(3):491-497.
Intended for U.S. audiences only
Participate in XLH Research
To talk to someone and get more information about Ultragenyx clinical trials and research, email [email protected].
Disease Monitoring Program
The BEYONDXLH disease monitoring program (DMP) collects and tracks health information from children and adults with XLH. BEYONDXLH is a non-interventional, prospective, observational DMP conducted through a mobile/web-based application.
For more info, visit beyondxlh.com or clinicaltrials.gov.
Research plays a critical part in advancing science and treatments. Volunteers who participate in this research are essential. Future therapies would not be possible without them. Participating in clinical trials, interviews, observational studies, and disease monitoring programs help to drive research, treatment development, and disease education. It is also a way to advocate for yourself and your community.
Upcoming Community Events
Participate in Events Near YouJul 14
Join the MAGIC Foundation for an educational experience for parents of children living with an endocrine disorder. World renowned speakers from across the globe will present on physical health, mental […]
Jul 22
Join MitoAction and the International Network for Fatty Acid Oxidation Research and Management (INFORM) for the 3rd Annual International Metabolic Conference for Fatty Acid Oxidation Disorders (FAODs) held in Pittsburgh, […]
Sep 1
In September, organizations across the country raise awareness about the importance of screening newborns for potential illnesses and genetic disorders. Learn more
*These organizations are an incomplete listing of rare disease advocacy groups and are not controlled by, endorsed by, or affiliated with Ultragenyx Pharmaceutical Inc. The list is meant for informational purposes only and is not intended to replace your healthcare professional’s medical advice. Ask your doctor or nurse any questions you may have about your disease or treatment plan. If you would like to have your group added to the list, please contact [email protected].
Rare Experiences
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Marah
X-linked Hypophosphatemia (XLH)“Nobody has the same story, but I hope siblings of those with rare conditions will take comfort in knowing that they are not alone.”
Cheryl
X-linked Hypophosphatemia (XLH)“Having a rare disease, I can’t control my symptoms, but I can control my attitude.”
