PHEX

PHEX (Phosphate regulating endopeptidase homolog, X-linked) is a gene that encodes a type of protein known as an endopeptidase. This protein plays a crucial role in the regulation of phosphate homeostasis, which is essential for many biological processes, including bone mineralization and cell function.

Function

The PHEX protein is primarily expressed in bone and teeth, where it is involved in the regulation of phosphate reabsorption. It does this by degrading a hormone called fibroblast growth factor 23 (FGF23), which inhibits phosphate reabsorption in the kidney. When the PHEX protein is not functioning properly, FGF23 levels can become abnormally high, leading to a decrease in phosphate reabsorption and subsequent phosphate wasting.

Clinical significance

Mutations in the PHEX gene are associated with a rare genetic disorder known as X-linked hypophosphatemia (XLH). This condition is characterized by low levels of phosphate in the blood, which can lead to rickets in children and osteomalacia in adults. Symptoms of XLH include bone pain, muscle weakness, and short stature. Treatment typically involves phosphate supplements and active vitamin D.

Research

Research into the PHEX gene and its associated protein is ongoing, with scientists hoping to better understand its role in phosphate homeostasis and its implications for conditions like XLH. This could potentially lead to new treatments and therapies for these conditions in the future.

File:PHEX gene location.png

Location of the PHEX gene on the X chromosome.

See also

• Endopeptidase
• Phosphate homeostasis
• X-linked hypophosphatemia