KCNJ10 and major depressive disorder: Conversely, down-regulation of KCNJ10 mRNA (encoding inwardly rectifying potassium channel (Kir)2q14.1 in the hippocampus) and SCN1A mRNA (encoding voltage-gated sodium channel (NaV) 1.1 in the PFC) has been observed in MDD patients [47, 48].