Moreover, recent work from our group demonstrated that PQQ increased RFC function at the arachnoid barrier (AB), implying that RFC upregulation via NRF-1/PGC-1α at the BBB, the AB, and brain parenchyma may collectively contribute to brain folate uptake in CFD, where folate transport into the CSF is compromised [57]. Here, PPARGC1A is linked to fleck corneal dystrophy.