THE CONTRIBUTIONOF GENETICSTO UNDERSTANDING SUICIDE

Epidemiological genetic studies provide good evidences that suicidal behaviour is familial, and that a substantial proportion of the variation in liability is explained by genes. Candidate gene approach studies suggested that serotonin (i.e. SERT, MAO, TPH 1 and 2) is involved along the pathway from genetic predisposition and environmental stimulus to expression of psychiatric disorders and suicidal behaviour. A further step in our knowledge on genetics of suicide comes from Gene-Environment interaction (GXE) studies. Caspi et al. (2003) found that a genetic polymorphism in the promoter of the serotonin transporter gene affects the likelihood of life stresses precipitating depression and suicidal ideation and attempts. Recently, Genome Wide Association Studies (GWAS) have demonstrated a great potential for individuating new genes associated with suicidal behaviour, principally because they examine a large set of gene polymorphisms without selecting one from an artificial hypothesis. Finally the Epigenetics perspective, the study of inherited and acquired modifications of DNA and histones occurring without a change in nuclear DNA sequence, could transform our understanding about the molecular etiology of complex disorders. We need to improve our knowledge on the mutual links that exist between DNA sequence, gene expression and protein synthesis and to continue on the road of gene environment interaction studies, testing more candidate endophenotypes and their interactions with traumatic and non-traumatic life events.