Considering the aforementioned background, the assessment of the white blood cells of patients with MDD to measure the gene expression of 11 acetone deacetylase showed that in MDD, a significant increase in the expression of histone deacetylase 2 and 5 was observed in the depressed cases as compared to the healthy controls (HDAC2 p< 0.001and HDAC5 p = 0.001) [49]. The gene discussed is HDAC5; the disease is major depressive disorder.