The role of the genetic polymorphism in the response to treatment and survival for oncological patients is well known.15,16 However, the genetic polymorphism of serotonin transporter (SERT) in causing an increased risk of depression in subjects who experienced stressful life events is also known and it has been initially reported by Caspi et al..17 In the prospective-longitudinal study of a representative birth cohort, the authors tested why stressful experiences lead to depression only in some subjects. The gene discussed is SLC6A4; the disease is major depressive disorder.