PHEX and X-linked hypophosphatemia: X-linked dominant hypophosphatemic rickets (XLH, OMIM 307800) is a rare heritable disease due to mutations of the PHEX gene, which leads to renal phosphate wasting and subsequently to hypophosphatemia; rickets with bone deformities; short stature; dental anomalies; normal serum calcium; urinary calcium excretion is typically low-to-normal; normal or low serum level of vitamin D (1,25(OH)2D, or calcitriol); and increased activity of serum alkaline phosphatase (Gohil and Imel, 2019).