ENPP1 and pseudoxanthoma elasticum (inherited or acquired): Patients with ENPP1 variants have very low to barely detectable PPi levels; this has been associated with early onset of arterial calcification.(11) Similarly, adult patients with ABCC6 deficiency and PXE diagnosis exhibited ~50% reduction in plasma PPi levels; consistent findings were reported in Abcc6‐mutated mouse models.(12, 13) It is not clear why some patients with ABCC6 variants present with arterial calcification at infancy, whereas others present with PXE as adults.