There are several hypophosphatemic diseases associated with increased FGF23, such as autosomal dominant and recessive hypophosphatemic rickets/osteomalacia (ADHR, ARHR) [150,151], X-linked hypophosphatemic rickets/osteomalacia (XLH) [152], hypophosphatemic rickets/osteomalacia associated with McCune–Albright syndrome (MAS)/fibrous dysplasia (FD) [153], or epidermal nervous syndrome [154]. This evidence concerns the gene FGF23 and X-linked hypophosphatemia.