Genetic predisposition of suicidal behavior: variants in GRIN2B, GABRG2, and ODC1 genes in attempted and completed suicide in two Balkan populations

Completed suicide accounts for over 700,000 deaths worldwide annually, while attempted suicide is 20 times more frequent. Genetic background is an important factor contributing to suicidal behavior, including candidate genes in glutamate, γ-aminobutyric acid (GABA), and polyamine systems. Our aim was to differentiate genetic predispositions underlying different types of suicidal behavior, attempted and completed suicide, in two Balkan populations. Analysis of variants in the genes GRIN2B (rs2268115 and rs220557), GABRG2 (rs424740), and ODC1 (rs1049500 and rs2302614) was performed on a study sample including 173 suicide attempters with comorbid psychiatric disorders, 216 non-suicidal psychiatric patients and 172 healthy controls from Serbia, and 333 suicide completers and 356 non-suicidal autopsy controls from Slovenia. CA genotype of rs220557 in GRIN2B gene increased the risk for completed suicide (P = 0.021), and violent suicide (P = 0.037), compared to controls. In ODC1 gene, CA genotype of rs2302614 decreased the risk for completed suicide compared to suicide attempt (P = 0.012). Marginally, AC haplotype for variants rs1049500-rs2302614 in ODC1 gene decreased the risk for completed suicide compared to suicide attempt (P = 0.052). Specific genetic variants of glutamate and polyamine systems are differently distributed among diverse suicidal phenotypes, providing further information on the implication of these systems in suicidality.