PHEX and X-linked hypophosphatemia: Approximately 63% to 89%% of inherited HR cases are due to pathogenic PHEX variants and result in XLH; the remaining cases are due to mutations in other genes involved in the synthesis, signaling, and regulation of FGF23, including FGF23, ALPL, CYP27B1, DMP1, and ENPP1 [3].