Table 4.

Genetics

Characteristic	Number of studies	Positive association	No association	Conclusion
Family history	4	Three studies identified a positive correlation between family history of suicide (behaviour/attempt) and suicide	One study found no difference	Positive family history
Biological markers	1	–	No difference in CSF 5-HIAA levels and CSF HVA levels between suicide attempters and non-attempters	No association between CSF 5-HIAA and HVA levels, and suicide
Genetics	2	One study: COMT Del Allele confers susceptibility to suicide attempters. One study: difference in mean ratios, with the ‘C’ alleles showing lower cDNA levels in the suicide group; decreased total 5-HT2A receptor mRNA in suicide victims	–	Genes identified to be associated with suicide – COMT Del Allele, “C” alleles and 5-HT2A receptor