The natural history of GACI, in particular its mortality, relation to rickets, and phenotypic differences based on genetic loci, has not been comprehensively elucidated, limiting effective diagnosis, prognosis, and management.(4, 7) This study describes the natural history of GACI, role of bisphosphonates in survival, and phenotypic similarities/differences between ENPP1 and ABCC6 deficiencies. The gene discussed is ENPP1; the disease is rickets.