The inactivating variants of ENPP1 also cause ectopic calcification and over-mineralization in arteries, ligaments, and skin matrix, leading to various allelic disorders such as generalized arterial calcification of infancy (GACI), early-onset hearing loss, ossification of posterior longitudinal ligament (OPLL), and pseudoxanthoma elasticum (PXE) (3–6). This evidence concerns the gene ENPP1 and Pseudoxanthoma elasticum.