ENPP1 and autosomal recessive hypophosphatemic rickets: Autosomal dominant hypophosphatemic rickets (ADHR; MIM 193100) usually correlates with mutations in the fibroblast growth factor 23 (FGF23; MIM 605380) gene [5], whereas mutations in two other genes are implicated in causing the autosomal recessive form, including the dentin matrix acidic phosphoprotein 1 (DMP1; MIM 600980) gene associated with autosomal recessive hypophosphatemic rickets-1 (ARHR1; MIM 241520) [6], and the ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1; MIM 173335) gene related to autosomal recessive hypophosphatemic rickets-2 (ARHR2; MIM 613312) [7].