Slc20a2 is critical for maintaining a physiologic inorganic phosphate level in cerebrospinal fluid

Mutations in the SLC20A2 -gene encoding the inorganic phosphate (Pi) transporter PiT2 can explain approximately 40 % of the familial cases of the rare neurodegenerative disorder primary familial brain calcification (Fahr’s disease). The disease characteristic, cerebrovascular-associated calcifications, is also present in Slc20a2 -knockout (KO) mice. Little is known about the specific role(s) of PiT2 in the brain. Recent in vitro studies, however, suggest a role in regulation of the [Pi] in cerebrospinal fluid (CSF). We here show that Slc20a2 -KO mice indeed have a high CSF [Pi] in agreement with a role of PiT2 in Pi export from the CSF. The implications in relation to disease mechanism are discussed.