For instance, the presence of genetic variants within the FKBP prolyl isomerase 5 (FKBP5, also known as FKBP51), a gene encoding enzyme related to the functioning of steroid hormone receptors [4], has been found associated with suicide attempts and depression-related Beck Depression Inventory (BDI) score [5, 6]. Here, FKBP5 is linked to major depressive disorder.