To understand the pathophysiology of these disorders we begin by examining the clinical phenotype and presentation of GACI infants, expand into the skeletal mineralization disorders associated with ENPP1 deficiency, and conclude with a discussion of the development of novel therapeutics for patients with ENPP1 deficiency and their application to mineralization disorders affecting the general medical population. This evidence concerns the gene ENPP1 and hyperinsulinemic hypoglycemia, familial, 4.