CAMK2G and major depressive disorder: Calcium/calmodulin-dependent protein kinase II (CaMKII) is an important enzymatic molecule present widely in animal cells that affects the functioning of neurons and cardiac cells by regulating calcium ion concentrations.[11,12] A recent study has shown that in a mouse model of depression, both the expression of CaMKII and its phosphorylation were significantly reduced.[13] However, no clinical studies have focused on the serum levels of CaMKII in HVS patients and its relationship with patients’ depressive conditions.