History and geography of suicide: Could genetic risk factors account for the variation in suicide rates?

Abstract

The current state of knowledge of genetic predisposition towards the suicidal behavior allows for a question whether genetic risk factors account for the variation in suicide rates through time and space. Accordingly, the presented paper will attempt to tackle the genetics behind suicidal behavior from the perspective of the populational genetics. First, the variability of suicide rates across Europe is discussed. This is followed by a brief discussion of the J curve (on a map of Europe, the countries with a higher suicide rate form a so-called J curve, which starts in Finland and extends down to Slovenia), which maps on to the second principal component identified for European gene distribution, representing the ancestral adaptation to cold climates and the Uralic language dispersion. Furthermore, we will discuss whether the group of people living within the J-curve could share genes, which may not tolerate excessive amounts alcohol, the combination of which is more likely to end in suicidal behavior. Further along we list possible ways in which suicidal behaviour could have been selected for genetically in populations and identify those specific populations in which it may have appeared. Finally, we point at other locations in the world where a similar interplay of genes and environment has probably occurred, Greenland being the best example of the malignant interaction of alcohol consumption and the trait-like characteristics, which might constitute the vulnerability to suicidal behaviour.

A W148R mutation in the human FOXD4 gene segregating with dilated cardiomyopathy, obsessive-compulsive disorder, and suicidality

“…The most important finding from this study possibly is the identification of FOXD4 as a potential candidate for suicidal behaviour. Although it is well-known that suicide runs in families and that genetic factors may contribute to suicidal behaviour (19), the great majority of molecular genetic studies has been focused on polymorphisms in serotonergic genes (20). Nonetheless, in line with previous observations (21), our present data indicate that molecular pathways other than the cerebral neurotransmission systems may play a pivotal role in the genetic vulnerability for suicidal behaviour.…”

Genetics of suicide: a systematic review of twin studies

“…Supportive evidence comes from quantitative genetic studies based on the classic family, twin and adoption designs of behavioral genetics [3][4][5][6] and, more recently, from molecular genetic studies of candidate genes, in particular those involved in the serotonergic neural transmission system [7,8], as well as from genome-wide linkage scans for genetic variants associated with risk of suicide [9,10]. These convergent lines of evidence are further complemented by supporting findings from a number of other research strategies, such as geographical studies [11][12][13][14][15][16][17], immigrant studies [18,19] and surname studies of suicide [20,21].…”

Genetics of suicide

“…5 Several explanations have been considered for national and regional variations, including climate, religion, social and political systems, but a more likely scenario is that the genetic contributions to suicide will be represented by small size effects of many gene variants associated with processes involved in suicidal behaviour, and by interaction of these genetic factors with environmental factors. 3,6 Defining the phenotype Suicidal behaviour includes a wide spectrum and refers to the occurrence of suicide attempts that range from fatal acts (completed suicide) over highly lethal, but failed suicide attempts (where high intention and planning are evident and survival is fortuitous) to low lethality, usually impulsive attempts triggered by a social crisis which contain a strong element of an appeal for help. 7 Suicidal ideation, which comprises suicidal thoughts or threats devoid of action, is more common than suicide attempts and completed suicide and its prevalence varies widely, being almost twice in females compared to males.…”