TPCN2 and posterior cortical atrophy: TPC channels, TPC1 and TPC2, are highly Na+-selective channels (PCa/PNa ∼0.1) in the lysosomes, although their Ca2+ permeability may become significant (PCa/PNa ∼0.7) if the channels are activated by NAADP and certain synthetic agonists (Brailoiu et al., 2009; Calcraft et al., 2009; Gerndt et al., 2020; Wang et al., 2012; Yuan et al., 2022; Zong et al., 2009; Fig. 3).