PRRT2 and Parkinson disease: Since PKC activation influences the process of cognition through regulating phosphorylation of substrates such as N-methyl-D-aspartate (NMDA) receptor, AMPA receptor, and growth-associated protein-43 (Sun and Alkon, 2010), the expressions of several PKC isoforms are down-regulated in cognition impairment conditions, including aging, PD, and AD (Mizutani et al., 1998; Alkon et al., 2007; Do Van et al., 2016).