Association between polymorphisms of NOS1, NOS2 and NOS3 genes and suicide behavior: a systematic review and meta-analysis.

The enzyme nitric oxide synthase has been associated with suicide behavior. NOS1, NOS2 and NOS3 genes are implicated in the production of nitric oxide. However, the association between NOS genes and suicide behavior has not yet been established. To assess the association of Nitric Oxide Synthase (NOS) genes and suicide behavior we performed a systematic review a meta-analysis. We searched articles published in three electronic databases, PubMed, Scopus and Web of Sciences, up to February 2019. We used keywords and combinations "NOS", "NOS1", "NOS2", "NOS3" and "suicide". Only articles that met the inclusion criteria were included. To assess the association between NOS genes and suicide behavior we used allelic, dominant and recessive models, as well as homozygous and heterozygous comparisons. The pooled results showed that rs2682826 of Nitric Oxide Synthase 1 gene (NOS1) increased the risk for suicide attempt in the allelic (OR: 1.34; 95 CI: 1.00-1.78), recessive (OR: 1.45; 95 CI:1.06-1.98) and heterozygous (OR: 1.41; 95 CI: 1.09-1.81) models. We found that the rs2682826 of NOS1 could increase the risk for suicide attempt. However, these results should only be taken as exploratory; more studies are necessary to determine the association between NOS genes and suicide behavior.