Genetics of suicide?

[Apollyon]

I just found out that another distant family member (cousin that I didn't know) killed herself a few days ago. This one hanged herself, as did a cousin 5 yrs ago and a more distant relative 2 yrs ago, and a second cousin shot himself 3-4 years ago. I didn't know any of them too well (and two of them, I never met in my life), but I hadn't heard about any outstanding mental illness or hospitalization (in our family, the news gets around, even if we don't know the people).

The link is my father's paternal grandmother. All of the four people that killed themselves were from the family branch of my father's father's mother (two directly descended from her - both first cousins, and the other two descended from siblings of my father's paternal grandmother). History for other members is sketchy, as that goes back to emigration from Poland. I do know that my paternal paternal great grandfather (my father's father's father) had a family - wife and kids - in Poland, and up and left them there, came to the US, and started a family. His wife is the one with the descendant suicides. What makes it interesting is that the great grandfather from Poland got killed in an industrial accident, and his wife (the link) remarried, and there is one suicide in the line of the first husband, and three in the other or sibling (which demonstrates the link).

So, my question is about the genetics of suicidality. Sometimes folks are depressed, others are bipolar, some are borderline, and others are psychotic. Last year, I asked an addiction doc I know about the genetics of alcoholism - he said there was a genetic link, and he provided a bunch of studies, but I asked him "Which genes?", and I didn't get a straight answer.

Has any researcher pinned down a certain locus on a certain chromosome, or what is the current thinking about genetic linkage of suicide? I ask this as a dispassionate doc in the ED.

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[loveoforganic]

The concept that genetic factors contribute to the complex trait of suicidal behaviour has stimulated much work aimed at identifying susceptibility genes. So far molecular genetic studies focused on the serotonergic pathway as the intent to die and the lethality of suicide acts were related to the serotonergic system. Two genes have so far emerged as being involved in the vulnerability for suicidality: first, the intronic polymorphisms (A218C or A779C) of the tryptophan hydroxylase 1 (TPH1) gene, which was suggested as a quantitative risk factor for suicidal behaviour; second, the insertion/deletion polymorphism of the serotonin transporter gene (5-HTTLPR), which does not seem to be involved in general suicidal behaviour, but in violent and repeated suicide attempts. The data have further shown that the MAOA gene, which is consistently associated with impulsive-aggressive personality traits, is not related to suicide but might induce violent methods in subjects with other suicide risk factors. Predominantly negative were the findings with any type of the serotonin receptors and inconsistent with catecholamine-synthesizing and -metabolizing enzymes or with the dopaminergic receptors. This paper reviews the status of current knowledge in this area, points to the weakness of the investigations and presents new approaches beyond the serotonergic system.Molecular Psychiatry (2006) 11, 336–351. doi:10.1038/sj.mp.4001803; published online 7 February 2006


I can get you the article if you want. This would be just one set of risk factors. As with almost all things behavioral, heritable stuff is probably polygenic, and there are probably multiple sets of polygenic risk factors at play.

 

[Apollyon]

Dude, that is MONEY! Exactly about which I was asking. Another colleague PMed me an article. If you have a link to that article, it would be great. Although, as you've given me the citation, I'll see if I can access myself, too.

Thank you! And I know about environment along with genetics, so that is why I specifically state that I am not seeking medical advice - I already see my own doctor when I have questions!

 

[loveoforganic]

FT pdf attached below. Just to be clear, I didn't only mean that environment is at play too. Something like sickle cell might be monogenetic, but even a single risk factor for suicide, such as impulsivity, is likely polygenetic. Likewise for each of the various risk factors. So there's probably a very large variability in the effect genetics can have on any one person.

 

[xela007]

Interesting post.

I have never read or had the power to read much about suicide but now I'm trying to find a bit more about it, since my father has committed suicide back 12 years ago and never really understood why (apart from the fact that he was diagnosed with paranoid personality disorder)

There haven't been any other cases in our entire family history.. there were a two cases that I am aware of mild depression but never psychosis or suicide.

Thanks for sharing the pdf. article.

 

[GH253]

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[GH253]

There is not even a proven physiological basis for depression, let alone has anyone identified genes reponsible for an as of yet unknown pathophysiology, if any exists.

A person commits suicide because his judgment informs him that 1) it is acceptable to do so (from his perspective, the only one that matters), and 2) death is preferable to whatever circumstances the person faces if he continues to live. Whether the person's judgement is correct is irrelevant; the point is that the decision to commit suicide is determined by the ideas in his head, not his genetics.