ABCC6 and pseudoxanthoma elasticum (inherited or acquired): As a result of nonfunctional ABCC6 transport activity, plasma PPi levels in patients with PXE and Abcc6 knockout murine models of PXE are reduced to approximately 30%–40% of controls (Li et al., 2017; Jansen et al., 2014; Kowal et al., 2021; Saeidian et al., 2022).