These investigations were used for assessing biomarkers of depression including Interleukin 6 (IL-6) (ELISA KIT‘, Sino Gene Clon Biotech Co.,Ltd, Detection range 4.7 ng/L −800 ng/L), Tumor necrosis factor alpha, TNF-α (ELISA KIT‘, Sino Gene Clon Biotech Co.,Ltd, Detection range 15.6 ng/L −1,000 ng/L) and Coenzyme Q10 (CoQ10) (ELISA Kit, Sino Gene Clon Biotech Co.,Ltd, Detection range: 1.56 ng/ml −50 ng/ml). This evidence concerns the gene KIT and major depressive disorder.