Molecular genetics in the analysis of suicide.

Each year, one million people die of suicide. Among the different identified risk factors, genetic factors seem to be part of a multidimensional behavior, including psychiatric, psychosocial, biological factors and physical illness. Family studies have provided evidence for familial transmission in suicide, confirmed in twin and adoption studies. At a molecular level, serotonin seems to be one of the key neurotransmitters implicated in suicidal behavior. Therefore, genes coding for proteins involved in serotonergic neurotransmission have been extensively studied in case-control association studies on suicide. Major findings concern Tryptophan hydroxylase (TPH) gene, particularly in violent suicidal behavior. Though they may seem contradictory, studies on Serotonin transporter (5-HTT), Monaomine oxidase (MAOA), Serotonin 2A and 2C receptors (5-HT2A and 5-HT2C) and Tyrosine hydroxylase (TH) genes are promising. In spite of those observations having some limitations, it appears that genetic factors are a serious risk factor, besides environmental aspects of suicidal behavior.