X-linked hypophosphatemia (XLH) is a genetic disease. People with XLH have higher levels of a hormone called fibroblast growth factor 23 (FGF23). FGF23 lowers the amount of phosphate in the blood. The low level of phosphate may lead to bones that cannot grow and harden properly.
In most cases, XLH is an inherited disease, which means parents pass XLH down to their children. If you or your child have XLH, other people in your extended family may have it, too.
X-linked means that the gene affected is on the X chromosome. Females have two X chromosomes, while males have one X chromosome and one Y chromosome.
If a mother has XLH:
If a father has XLH:
In about 20% of cases, a person develops XLH without any family history.
