FAM20C and lethal osteosclerotic bone dysplasia: ,4 Other inherited forms of hypophosphatemia are also known, such as autosomal dominant hypophosphatemic rickets due to FGF23 variants (ADHR, MIM #193100), autosomal recessive hypophosphatemic rickets due to DMP1 (dentin matrix protein 1) (ARHR1, MIM #241520) or ENPP1 variants (ectonucleotide pyrophosphatase/phosphodiesterase 1) (ARHR2, MIM #613312), and the extremely rare Raine syndrome (RNS, MIM #259775) due to FAM20C variants (Golgi associated secretory pathway kinase).1