X-linked hypophosphatemia

Overview
X-linked hypophosphatemia (hypophosphatemic rickets, vitamin D-resistant rickets) is an X-linked dominant form of rickets (or osteomalacia) that differs from most cases of rickets in that ingestion of Vitamin D is relatively ineffective.

It is associated with the gene PHEX on chromosome Xp22.1, which encodes a product that inactivates hormone-like substances (phosphatonins) that promote phosphate excretion and impair bone mineralization.