PRA Health Sciences
PRA Health Sciences

My husband and I always suspected that something was amiss with our first child, Olivia*. Her legs were severely bowed and she did not walk or run like kids her same age. At every well-child check we would ask her pediatrician about it. We were assured that young children often have bowing in their legs.

But mother’s intuition told me that this was not normal.

Olivia continued to fall off her growth charts. We kept asking questions, and finally, our pediatrician referred us to a pediatric orthopedic doctor.

The appointment did not last long and resulted in us receiving a piece of paper about how “tibial torsion,” an inward twisting of the shin bones, resolves for 99% of children by the time they turn four. I left that appointment trying to convince myself that Olivia would grow out of this within a year.

But deep inside, I still had doubts.

At around three years old, Olivia began to complain about her knees buzzing and being tired. When she began limping without any signs of injury to her legs, I immediately took her back to the pediatrician, and later an occupational therapist, a physical therapist, a radiologist and eventually an endocrinologist.

It was the endocrinologist who told us Olivia had “hypophosphatemia.”

Finally, we had a diagnosis.

We weren’t quite there yet, however: We were told Olivia didn’t have the most common form of hypophosphatemia, X-Linked Hypophosphatemia (XLH), because only males were able to get XLH.

As many parents would, I researched hypophosphatemia as much as I could. I joined The XLH Network. A member contacted me immediately and asked about my daughter. When I stated that we were told that girls did not get XLH, the member responded that she was, in fact, a female with XLH.

Getting answers

Through The XLH Network, I have learned that XLH is a rare form of rickets not caused by a failure to obtain enough Vitamin D but rather the body’s inability to retain phosphorus. XLH affects both males and females and is lifelong. Those with XLH can exhibit bowing of the legs, pain, tooth abscesses, and short stature, amongst other symptoms.

Looking back, Olivia had nearly all of the symptoms of XLH. Some children have extensive family histories of XLH as it is a genetic disorder passed through the X chromosome. Olivia is a spontaneous case, meaning there is no family history and the condition is the result of a genetic mutation not passed on. Neither her father, her younger brother, nor I have XLH. That’s because often, XLH is caused by a mutation in the PHEX gene.

Now five, Olivia refers to her condition as having “soft bones.” Those with XLH face several challenges. For Olivia that means bone pain, short stature, and tooth abscesses. With treatment, the bowing has begun to subside and her pain has lessened but she still struggles with pain after activity. We know that into adulthood, there can be limited mobility and increased pain.

Those with XLH are often misunderstood by medical professionals who have limited knowledge of this rare condition. This lack of education and understanding can be isolating.

Life with XLH

Olivia participates in gymnastics and ballet and is often climbing everything she can on the playground. It is difficult as a mother not to hold her back for fear she may have an increase in pain or cause more pain to herself later in life. But teaching her that she can do anything she puts her mind to is important. I have learned that the best thing we have done for a child with a rare condition is to find medical professionals that have a thorough understanding of that rare condition. For us that means traveling thousands of miles.

There have been several clinical trials for XLH, but currently, the only treatment option available to the public is to take phosphorus and Calcitriol in doses directed by a physician. A new drug, KRN23, that is being developed by Ultragenyx Pharmaceuticals works by helping the body retain phosphorus.

A family united

For families living with XLH, The XLH Network provides parents with the vital tools they need to advocate for their children. Without The XLH Network connecting us with other members, we would not have found knowledgeable doctors to provide us expert advice and connect us with relevant research trials. It’s also been a source of support for us when we have questions about the kinds of activities children with XLH can participate in or if we have medical issues come up that we are not sure are related to XLH. For any family dealing with a rare disease patient advocacy is essential.

I have been so thankful to The XLH Network for connecting our family with Dr. Thomas O. Carpenter and the XLH team at Yale-New Haven Hospital. Their knowledge and experience with XLH has been a great benefit. Without Dr. Carpenter and his team, our daughter would not be living the remarkable life she now has.

*Name changed to protect identity.