Suicide between humanism and science. Suicide is among the first 10 causes of death in industrialized countries, even if its incidence is declining. Familiarity frequently occurs in suicide and a myriad of polymorphisms in candidate genes has been studied as risk factors. Among these, genes encoding enzymes, transporters or receptors of the serotoninergic and dopaminergic systems have been widely studied with conflicting results. Also the metabolism of cholesterol (and serum cholesterol concentrations) seems to have a role in the pathogenesis of suicide. In the last years, our group contributed to study brain derived neurotrophic factor (BDNF) and its TrkB receptor genes in the DNA from Wernicke area from a large cohort of suicide subjects and controls. In particular, we excluded that the expression of BDNF and its receptor may be modulated by gene mutations. However, the levels of BDNF gene expression were significantly lower in the brain tissue from suicide subjects. We demonstrated that the altered BDNF expression was due to the enhanced methylation of BDNF promoter. These studies first revealed the association between epigenetics and suicide suggesting a novel model of interaction between environment and genes in the pathogenesis of suicide.