PHEX and hypophosphatemia: It is considered the most common hereditary form of hypophosphatemia (1 in 20,000 births), and results from the loss-of-function of the phosphate-regulating neutral endopeptidase (PHEX) enzyme (Burnett et al., 1964; “Orphanet Report Series, 2017 – Prevalence of Rare Diseases: Bibliographic Data – June 2017 – Number 1” 2017).