Are you worried about your child's bones? Let's learn about XLH (X-Linked Hypophosphatemia)!

Is your little one late to walk? Or do their legs look a little bowed? Sometimes these could just be normal. However, sometimes there could be a condition behind them like XLH (X-Linked Hypophosphatemia) . Let's talk about this a little bit today, shall we? Don't worry, I'll help you understand all this.

What does XLH mean? Let's understand it simply!

Simply put, XLH (X-Linked Hypophosphatemia) is a genetic disease. That is, a condition caused by a small change in the genes in our body. It mainly affects your bones and teeth . You may have heard of the disease called ``Rickets``? Well, XLH is a type of rickets. Young children with this condition may have difficulty walking, their legs may be bowed. Not only that, but they may also have other problems such as muscle weakness and hearing loss.

What are the symptoms of XLH? Let's be a little careful!

Symptoms of XLH usually appear in early childhood. However, some symptoms may also appear in adulthood.

Symptoms in young children:

Here are some things you should pay attention to:

• Difficulty walking or delayed starting to walk.
• Bowing legs or knock knees, as if a large ball is passing between the legs.
• Pain in the bones and muscles. Does your little one often say, "Oh, my legs hurt"?
• Decreased height (short stature).
• Feeling lifeless and tired all the time.
• Muscle weakness.
• Dental problems: premature loss of baby teeth, toothache, abscesses, frequent tooth decay.
• Changes in the shape of the head or face. Sometimes this can be caused by the bones of the skull fusing together too quickly (called `craniosynostosis`).

Additional symptoms that develop in adulthood:

As people with XLH grow older, additional symptoms may develop. These include:

• Hearing loss.
• Headache.
• Narrowing of the spinal canal (Spinal Stenosis).
• Softening of bones in adults (`Osteomalacia`).
• Loss of balance while walking, difficulty walking.
• Loss of permanent teeth.
• Thickening or tightening of ligaments or tendons.
• Joint stiffness, difficulty bending.
• Frequent fatigue.
• Fractures and pseudofractures (that is, where a bone looks like a fracture on X-ray, but is not actually a complete break).

What causes XLH? Why does this happen?

Okay, now let's see why XLH develops. The reason for this is a genetic mutation in the `PHEX` gene in our body. This `PHEX` gene produces a hormone called `FGF23` (`Fibroblast Growth Factor 23`). This `FGF23` hormone is very important. Because, it helps control the amount of phosphate in our body. Phosphate is essential for keeping our bones healthy.

This is what usually happens: If our body has enough phosphate, the hormone `FGF23` tells the kidneys, "Okay, enough now, let's get rid of the excess phosphate in the urine." However, if the body needs more phosphate, the production of the hormone `FGF23` decreases.

Now, the mutation in the `PHEX` gene causes our body to produce more `FGF23` hormone than it needs. Because of this excess hormone, the body excretes more phosphate than it needs in the urine. That's when the phosphate needed for bones and teeth is lost, and the symptoms of XLH appear. Do you understand?

Simply put: a change in a gene -> more of the hormone `FGF23` is produced -> more phosphate is excreted from the body -> bones become weak.

Is XLH hereditary?

Yes, this condition called XLH is inherited in an X-linked autosomal dominant pattern . This means that if someone has the gene with that genetic variation, they will develop the disease. It may affect boys slightly more .

Now look, a girl has two X chromosomes, a boy has one X chromosome and one Y chromosome. Since we each receive one sex chromosome (X or Y) from our parents:

• A woman with XLH generally has a 50% chance of passing this gene on to her child.
• A man with XLH passes this gene on to all of his daughters , but not to his sons.

However, sometimes a child can develop XLH even if neither parent has it. In such cases, the genetic change occurs randomly.

How do you know exactly if you have XLH?

If a doctor suspects you have XLH, they may do several tests, such as:

• Blood or urine tests: These check phosphate and FGF23 hormone levels .
• Genetic Testing: Check to see if there is a mutation in the PHEX gene.
• Bone Density Tests: Check how strong your bones are.
• X-rays or other imaging tests: Check the shape of the bones and whether there are any deformities.

What are the treatments for XLH?

Unfortunately, there is no cure for XLH yet. However, there are treatments that can help control symptoms and maintain bone health. The main goal here is not to bring phosphate levels back to normal (which may not be possible), but to maintain bone health.

The following can be done as treatment:

• Giving phosphate supplements and calcitriol (a type of vitamin D) .
• Burosumab : This is a monoclonal antibody that blocks the hormone FGF23.
• Physical Therapy (PT): Strengthen muscles and make walking easier.
• Occupational Therapy (OT): Helps you perform daily tasks more easily.
• Surgery to correct bone deformities (e.g., bowed legs).
• Giving growth hormones to those who are short in height.
• Hearing aids for the hearing impaired.

In addition, if things like bone fractures or dental problems occur, they will also require surgery or other treatment.

What can someone with XLH expect?

If you or your child has XLH, it is important to get a diagnosis and treatment as soon as possible . This can help prevent many complications. Sometimes, some bone deformities can go away on their own, or they may not cause any problems. However, in some cases, surgery or physical therapy may be needed to correct them. It is a good idea to talk to your doctor about this and ask what to expect.

What is the life expectancy of someone with XLH?

Studies have shown that the lifespan of someone with XLH can be about eight years shorter than someone without the condition. However, experts are still not sure what exactly causes this difference in lifespan.

Can XLH be prevented?

XLH is a genetic condition, so it cannot be prevented. However, if the disease is diagnosed very early and treatment such as Burosumab is started, children can develop normally and without symptoms . If you have XLH and want to know about the possibility of passing it on to future children, it is very important to talk to a genetic counselor .

If I have XLH, how do I take care of myself/my child?

When living with XLH, these things can help you care for yourself and your baby:

• Get genetic testing done. If the disease is confirmed, you can start treatment as soon as possible.
• See a dentist regularly so that problems with your teeth and gums can be identified early.
• Be sure to go to follow-up appointments every day you see your doctor. Don't skip things like physical therapy (PT) and occupational therapy (OT). Tell your doctor if you have any new symptoms or if your symptoms get worse.
• Take your prescribed medication exactly as prescribed, on time. If you have any questions about how to take your medication, or if you experience any side effects, tell your doctor.
• Engage in physical activity as recommended by your doctor. Ask him or her about safe exercises that will strengthen your bones.

When should I see a doctor?

If you have any concerns about your child's health or whether they are meeting developmental milestones, talk to your pediatrician . He or she will recommend further tests if necessary.

If you have XLH, see a doctor immediately if you develop new symptoms or if your symptoms get worse.

When do you need to go to the Emergency Treatment Unit (ETU) ?

See a dentist in the event of a dental emergency. For example:

• A severe toothache.
• A tooth is badly chipped or broken.
• A tooth that is loose or about to come loose (Extruded tooth).
• A dental abscess develops at the root of a tooth, causing swelling of the face and jaw.

What questions should I ask the doctor?

It may be helpful to ask questions like these when you see your doctor:

• What treatment options are available to me/my child?
• How can I protect my/my child's bone health?
• When should you go to the Emergency Room (ETU) ?
• When should I see you again?

Do children with XLH reach puberty?

Yes, absolutely. Children with XLH go through puberty and have growth spurts just like any other child. Don't be afraid of that.

Finally, what to remember

Being diagnosed with a lifelong condition can be a bit scary. You may wonder what your child's future – or your own future – will be like with XLH.

But remember, people with XLH can live long, healthy lives. Early diagnosis and proper treatment can go a long way in keeping your bones strong and healthy. Never hesitate to talk openly with your doctor about any concerns or questions you may have. He or she will be able to help you.

` XLH, X-Linked Hypophosphatemia, bone diseases, genetic diseases, rickets, phosphate, children's health, FGF23