Genetics of Suicidal Behavior

Suicidal behavior is a global public health problem. Patients with different psychiatric disorders, such as alcohol and substance use disorders, depression, bipolar affective disorder, schizophrenia, posttraumatic stress disorder (PTSD), personality disorders and altered behaviours frequently have suicidal thoughts, ideas and frequently develop suicidal behavior. However, there are a lot of psychiatric patients who do not have suicidal thoughts or suicidal ideation, who do not display suicidal behavior, and who never attempt suicide. Suicide is believed to be a multi-determined act, precipitated by a complex interplay of different socio-cultural factors, biological factors, traumatic events, a history of psychiatric disorders and particular personality traits. Neurobiological basis of suicidal behavior is not completely understood, however, the disturbances in the function of the major neuroendocrine and neurotransmitter systems, such as the hypothalamicpituitary-adrenal (HPA) axis, serotonin, noradrenalin, dopamine, gamma-amino butyric acid (GABA), glutamate, endogenous opioids, and plasma cholesterol status, are assumed to be responsible for the development of suicidal behavior. The evidence from the literature suggests that genetic factors play an important role in the predisposition to suicidal behavior. Therefore, the data from the family, twin, and adoption studies all point to a genetic predisposition to suicide and suicidal behavior. Genetic studies are focused on the search for the candidate genes related to suicide and suicidal behavior. The most frequently investigated genes are the genes related to serotonin, noradrenalin and dopamine transporters, receptors and enzymes involved in the synthesis and degradation of these neurotransmitters, genes related to glutamatergic system, GABA and to neurotrophic factors and genes related to neuroendocrine system. However, despite the numerous studies showing the association of particular genes and suicidal behavior, the genetic risk factors for suicidal behavior, such as susceptibility genes that contribute to suicidal behavior, are still not yet confirmed, and there are a lot of non-replication in these results. Since the transmission patterns of suicidal behavior is complex, involving both environmental and genetic factors, precipitated by the complex interactions of the multiple genes, multiple alleles are implicated in the development of suicidal behavior. Therefore, more studies are needed to fully understand the genetic basis of suicidal behavior. The search for the genetic risk factors of suicidal behavior is an important task in the studies of the genetic susceptibility to suicide, since these studies might help in identifying subjects prone to develop suicidal behavior, who might attempt and/or complete suicide. These subjects might be properly treated and suicidal behavior might be prevented, in order to decrease the suicide rate. Therefore, an important goal in psychiatry is to evaluate the risk factors of suicidal behavior, in order to prevent suicidal behavior, to early identify the individuals prone to attempt suicide, to use the best possible treatment strategies to save lifes and to prevent suicidal attempts and suicide.