Patients with X-Linked Hypophosphatemia (XLH) are living the theme of this year's Rare Disease Day: "Research brings hope to people living with a rare disease."
Virtually all of the estimated 7,000 identified rare diseases have no truly effective treatments available,
and until recently that was true of XLH. This year, though, XLH patients will be celebrating Rare
Disease day on February 28th with renewed hope as researchers are closing in on what appears to be an
XLH is a rare genetic disorder that affects approximately one in 20,000 people.
Patients produce an
excess of a hormone known as FGF23, which causes them to have low levels of phosphorus in the
blood. Without an adequate source of phosphorus, the body cannot form strong bones and teeth or
properly fuel muscles. In the absence of treatment, patients experience bone deformities (most
commonly bowed legs or knock-knees), short stature, spontaneous tooth abscesses, bone pain and
The role of FGF23 in the disorder was not known until 2000, when the hormone was first discovered.
Since then, research has provided preliminary answers to a number of questions about XLH, and even to
a proposed treatment, currently under review by the European Medicines Agency, and expected to be
submitted to the FDA in the second half of 2017.
Clinical trials of the new treatment, known as KRN23, have been promising so far. This Rare Disease
day, the XLH community is hopeful that with this treatment or others still in the pipeline, children born
in the future will grow up strong and energetic.
The mother of a one-year-old infant in a clinical trial of KRN23 notes that this research "means
everything to me." She goes on to say that "having this same rare disease and remembering the surgeries
and treatments I endured makes me extremely grateful that my daughter is included in this trial."
For parents of slightly older children, there is nothing like the thrill of seeing their children improve
noticeably. One mother of a ten-year-old girl notes that she hopes this research has led to a new therapy
that will not cause the same problematic side effects of the only other therapy available to XLH patients.
"Being part of a research trial has been intimidating," she says, "but it is so worth it. My daughter’s
health is clearly better, and we are helping to pave the way for others."
The new treatment also offers hope to older patients whose bones are long past the critical growing
years. One sixty-something XLH patient in a clinical trial of KRN23 hopes that the new treatment will
prevent her mobility restrictions from getting any worse. "I may walk slowly," she says, "but I get where
I need to go eventually. If my condition worsened, I might not be so independent, and that would be
Founded in 1996 and growing daily, The XLH Network, Inc., a 501(c)(3) non-profit, helps thousands of
people around the world who are affected by XLH and related phosphate-wasting disorders. With the
generous guidance of a Scientific Advisory Board, the Network engages in education, advocacy, and
patient support by providing up-to-date information on diagnosis, treatment, research and clinical trials
to patients, caregivers, medical providers, researchers and other key players in the medical services
industry. The Network also fosters the search for better treatments and ultimately a cure.
For more about the XLH Network: XLHNetwork.org
For more about Ultragenyx Pharmaceutical: Ultragenyx.com
For more about the KRN23 clinical trial data:
For more about Rare Disease Day 2017: www.rarediseaseday.org