Reports also suggest adults with monoallelic ENPP1 variants exhibit low ENPP1 activity, low PPi levels and FGF23‐mediated hypophosphatemia, and for these patients presenting with low bone mineral density, early‐onset osteoprorosis, or presentation of OPLL and DISH, a diagnosis of ENPP1 Deficiency should be entertained. The gene discussed is ENPP1; the disease is diffuse idiopathic skeletal hyperostosis.