Mutations in both alleles of the ENPP1 are associated with generalized arterial calcification of infancy (GACI1: OMIM #208000) (4, 5) and autosomal recessive hypophosphatemic rickets type 2 (ARHR2: OMIM #613312) (6). The gene discussed is ENPP1; the disease is hypophosphatemic rickets, autosomal recessive, 2.