ENPP1 and hypophosphatasia: Biallelic pathogenic variants of Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) have been identified in patients with a third FGF-23 mediated hypophosphatasia called ‘Autosomal Recessive Hypophosphatemic Rickets type 2’ (ARHR2: OMIM #613,312).