Abstract

Suicidal behavior as a psychological problem with high public health burden is associated with a number of genetically determined risk factors. In the current study, we investigated the association between two polymorphisms within the NINJ2 gene and risk of suicide in an Iranian population. The study included 295 individuals who attempted suicide with soft suicide methods, 234 suicide victims and 410 normal controls. The rs11833579 SNP was associated with death from suicide in a codominant model in that the AG genotype decreased the risk of death from suicide compared with the GG genotype (OR (95 CI) = 0.49 (0.34–0.71), adjusted P value = 4e−04). This SNP was also associated with death from suicide in dominant (AG + AA versus GG: OR (95 CI) = 0.63 (0.46–0.87), adjusted P value = 0.011) and overdominant (AG versus GG + AA: OR (95 CI) = 0.49 (0.35–0.69), adjusted P value < 0.0001) models. In addition, this SNP was associated with soft suicide attempts in a codominant model (AG versus AA + GG: OR (95 CI) = 0.7 (0.5–0.98), adjusted P value = 0.02). The rs3806263 SNP was associated with death from suicide in allelic (A versus G: OR (95 CI) = 1.48 (1.17–1.88), adjusted P value = 0.002), codominant (AA versus GG: OR (95 CI) = 3.14 (1.89–5.21), adjusted P value < 0.0001), recessive (AA versus GG + AG: OR (95 CI) = 3.47 (2.15–5.61), adjusted P value < 0.0001), overdominant (AG versus AA + GG: OR (95 CI) = 0.62 (0.45–0.87), adjusted P value = 0.0092) and log-additive models (OR (95 CI) = 1.45 (1.15–1.83), adjusted P value = 0.0034). When comparing allele/genotype frequencies of this SNP between suicide victims and soft suicide attempters, significant associations were found in allelic, codominant, recessive and log-additive models. The AG haplotype (rs11833579 and rs3806263, respectively) was significantly less prevalent among suicide victims compared with controls (OR (95 CI) = 0.37 (0.26–0.52), adjusted P value < 0.0001). This haplotype was also less prevalent among suicide victims vs. soft suicide attempters (OR (95 CI) = 0.43 (0.31–0.61), adjusted P value < 0.0001). The GA haplotype (rs11833579 and rs3806263, respectively) was less frequent among suicide victims compared with controls (OR (95 CI) = 0.63 (0.45–0.89), adjusted P value = 0.0156). Finally, the AA haplotype was more prevalent among suicide victims compared with both controls (OR (95 CI) = 2.37 (1.56–3.6), adjusted P value = 0.0002) and soft suicide attempters (OR (95 CI) = 1.92 (1.32–2.78), adjusted P value = 0.0012). Thus, these two SNPs might be regarded as genetic determinants of suicide risk in Iranian populations. Further studies in different populations are needed to verify these results. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.