Association study of a single nucleotide polymorphism in the hypoxia response element of the macrophage migration inhibitory factor gene promoter with suicide completers in the Japanese population

BACKGROUND

More than 800 000 people die by suicide annually. The heritability of suicide is 30%-50%. We focused on the hypoxia response element (HRE), which promotes the expression of macrophage migration inhibitory factor (MIF) via the hypoxia-inducible factor (HIF) pathway, important in neurogenesis and neuroprotection. We examined a genetic polymorphism of rs17004038, a single-nucleotide polymorphism (SNP), in suicide completers and controls.

METHODS

The study population included 1336 suicide completers and 814 unrelated healthy controls. All participants were Japanese. We obtained peripheral blood, extracted DNA, and genotyped the patients for SNP rs17004038 (C > A).

RESULTS

No significant differences were observed between the two groups in either the allele or genotype analyses. Subgroup analyses by sex, age (<40 or ≥40), and suicide method (violent or nonviolent suicide) were performed with similar results.

CONCLUSION

No association was observed between SNP rs17004038 and suicide completion. Although it is challenging to collect a large number of samples from suicide completers, further MIF-related genetic studies, including those of rs17004038, are necessary with larger sample sizes.

Association of two variable number of tandem repeats in the monoamine oxidase A gene promoter with suicide completion: The present study and meta-analysis

BACKGROUND

One potential cause of suicide is serotonergic dysfunction. Sex differences have been reported to modulate the effects of serotonergic polymorphisms. Monoamine oxidase A (MAOA) is an enzyme that degrades serotonin and is located on the X chromosome. A previous study indicated that the upstream (u) variable number of tandem repeat (VNTR) in the MAOA gene promoter may be associated with suicide. However, a meta-analysis showed that this polymorphism may not be related to suicide. According to a recent study, compared with the uVNTR, the distal (d)VNTR and the haplotypes of the two VNTRs modulate MAOA expression.

METHODS

We examined the two VNTRs in the MAOA gene promoter in 1007 subjects who committed suicide and 844 healthy controls. We analyzed the two VNTRs using fluorescence-based polymerase chain reaction assays. We conducted a meta-analysis for the two VNTRs to update it.

RESULTS

Our results demonstrated that neither the genotype-based associations nor allele/haplotype frequencies of the two VNTRs were significantly associated with suicide. In the meta-analysis, we did not indicate relationships between uVNTR and suicide nor did we identify articles analyzing dVNTR in suicide.

CONCLUSION

Overall, we did not find a relationship between the two VNTRs in the MAOA promoter and suicide completion; thus, warranting further studies are required.