Autosomal-recessive forms of hypophosphatemic rickets (ARHR1 and 2) are either caused by pathogenic variants in the dentine matrix acidic phosphoprotein 1 (DMP1) gene or in the ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) gene, which are both expressed in bone and teeth [53–56]. The gene discussed is ENPP1; the disease is hypophosphatemic rickets.