Findings from epidemiological studies utilising representative non-clinical samples are inconclusive; some have detected associations between C-reactive protein (CRP) and suicidal behaviour (Batty et al., 2016, Batty et al., 2018), while others fail to identify this association independent of psychiatric disorder (Bergmans et al., 2019, Russell et al., 2019). This evidence concerns the gene CRP and psychiatric disorder.