Depressive patients showed a decreased total nitrite content in the PMNs (~0.56 fold, p < 0.05, 95% CI: 0.05529 to 2.469), while the expression of the nNOS transcript was significantly more (~2.6 fold, p < 0.05, 95% CI: −0.006762 to −0.0003445) in the PMNs of these patients as compared to their first-degree relatives and the healthy volunteers (Figure 2C,D). This evidence concerns the gene NOS1 and major depressive disorder.