PHEX and X-linked dominant hypophosphatemic rickets: PHEX is composed of 749 amino acids and contains three domains: a short cytoplasmic N‐terminal region (amino acids 1‐20), a single transmembrane domain (amino acids 21‐37), and a long extra‐cytoplasmic domain (amino acids 38‐749), which contains zinc‐binding motifs as the active site of the enzyme.[1] To date, the Human Gene Mutation Database (HGMD) has reported more than 640 mutations of PHEX gene that are associated with XLHR.