XLH arises through pathogenic variants in the PHEX gene that are inherited in an X-linked dominant pattern or present as de novo variants, causing increased fibroblast growth factor 23 (FGF23) gene expression; elevations in circulating FGF23 levels lead to impaired renal phosphate conservation [1, 3-7]. This evidence concerns the gene FGF23 and X-linked hypophosphatemia.