X-linked Hypophosphatemia (XLH)
Overview of X-Linked Hypophosphatemia (XLH)
X-linked hypophosphatemia (XLH) is a genetic disorder that causes low levels of phosphate in the blood. It is an inherited condition that is passed on through genes in the X chromosome. People with XLH often have abnormally low levels of phosphate in their blood and may develop bone problems, including weak or malformed bones and stunted growth. Phosphate is an important mineral in the body that helps make up bones and teeth, and aids in cell metabolism and muscle function. A lack of phosphate can cause stunted growth and bone problems later in life.
XLH is caused by mutations in the PHEX gene, which provide instructions to make a protein involved in controlling phosphate levels in the body. This gene mutation occurs on the X chromosome. Since women have two X chromosomes, they may carry the defective gene but not experience any symptoms. A man, however, has only one X chromosome, so if he inherits the defective gene from his mother, he will typically develop the disorder.
Symptoms of XLH
Common symptoms of XLH include:
- Dental abnormalities, such as enamel defects, early tooth loss, and malformed teeth
- Short stature
- Bone pain
- Frequent fractures
- Curvature of the spine
- Delayed puberty and slow sexual development
- Bone and joint deformities
- Poor muscle tone
- Vision problems
Diagnosis and Treatment of XLH
A doctor may suspect XLH based on a person’s symptoms. Tests such as a physical examination, blood tests to measure phosphate levels, and imaging studies of the bones may be ordered to diagnose the condition. Treatment of XLH typically involves taking phosphate supplements and vitamin D to help increase phosphate levels in the blood and promote bone health.
In some cases, doctors may prescribe medication to help reduce symptoms. For example, bisphosphonates are a type of drug that can be used to treat osteomalacia, or softening of bones, which can occur with XLH. Physical therapy and other lifestyle changes may also be recommended to help improve muscular strength and mobility.
