Suicidal behavior is a complex phenotype that includes both attempted and completed suicide. Genetic epidemiological studies provide strong evidence for a heritable component to suicidal behavior, and the heritability for serious suicide attempts is estimated at 55%. Genetic association studies of suicidal behavior have focused on HPA-axis. Genetic variation in CRHR1 showed association and linkage to suicide attempt in depressed males exposed to low levels of stress. Immunophillin FKBP51 is expressed in cortical neurons and regulate the function of the glucocorticoid receptor (GR). Previous reports have shown that genetic variants in the FKBP5 gene encoding FKBP51 are linked to suicide. Alterations in the expression of the YWHAE gene cause the dysfunction of several neurotransmitters, such as serotonin, dopamine, and noradrenalin. Previous studies identified YWHAE gene as susceptibility gene for suicidal ideation and completed suicide.