MT-RNR1 and major depressive disorder: Despite the well-established link between elevated oxidative stress and neurological and psychiatric disorders, the inclusion of p66shc, MOTSc, and Humanin as key mitochondrial biomarkers provides new insight into the progression and severity of mental health diseases and strengthens the findings that mitochondrial peptide dynamics play an important role in the pathophysiology of depression, as well as providing an opportunity for a more comprehensive clinical intervention [72].