Background: Suicide is a critical global health issue that impacts individuals and communities around the world. Recent research suggests that inflammation may play a crucial role in the pathophysiology of suicide, but there is limited data available on genetic markers for inflammation in suicide. To address this gap, we conducted a study of genetic polymorphisms in cytokine genes among suicide completers in an Indian population. We examined five single nucleotide polymorphisms (SNPs) in three proinflammatory cytokine genes (IL-1?: rs1143627 and rs16944, IL-6: rs1800795 and TNF-?: rs1800629 and rs1799724).
Material and methods: A total of 490 unrelated individuals were included in our study, comprising 234 cases of suicidal death and 256 cases of non-suicidal death. The femoral blood sample was collected from each subject. Genotyping was conducted using the PCR-RFLP technique, which was validated through Sanger sequencing.
Results: The distribution of cases and controls was found to be unequal in terms of age, sex, and marital status. Males outnumbered females in both groups. The means of suicide adopted by subjects were predominately hanging (92%), followed by poisoning (5.98%). The most common precipitating factor reported was intrapersonal issues (16 %), followed by mental illness (9%) and substance abuse (7%). Our analysis revealed significant associations between specific single nucleotide polymorphisms (SNPs) and the risk of suicide. In the SNP rs16944, the major allele T was associated with an increased risk of suicide. In the case of SNP 1800795, both the CC and CT genotypes were associated with a higher risk of suicide compared to non-suicidal controls. Analyzing SNP rs1800629, the minor A allele was found to be protective. For SNP rs1799724, the minor allele (-850 T allele) was identified as a risk allele for suicide.
Discussion: Our findings are consistent with previous research on the association between some of these SNPs and depression or suicidal behavior, and provide new insights into the genetic factors that may contribute to suicidal behavior in this population. Alleles found to be associated with suicide were previously proven to be high-producing. Overall, this study agrees with the hypothesis that inflammation is significantly associated with suicidal behavior.