SLC20A2 and bilateral striopallidodentate calcinosis: Disruptions in Pi homeostasis are also operative in the disease idiopathic basal ganglia calcification (IBGP), which is a rare neurodegenerative disorder caused by inactivating mutations in the phosphate transporter SLC20A2/PiT2, PDGFR1-β, or PDGF-β (99–101).