Most HR types are FGF23-dependent, including X-linked dominant HR (XLHR) (MIM 307800, caused by mutations in PHEX), autosomal dominant HR (ADHR) (MIM 193100, caused by mutations in FGF23), autosomal recessive HR (ARHR) type 1 (MIM 241520, caused by mutations in DMP1), and autosomal recessive HR (ARHR) type 2 (MIM 613312, caused by mutations in ENPP1). The gene discussed is PHEX; the disease is X-linked dominant hypophosphatemic rickets.