SLC6A4 and Anxiety: For instance, the SERT−/− rodent model of depression/anxiety with a knock-out for the serotonin reuptake transporter has an aggregated large effect size for defensive/anxiety-related behavior relative to wild-type controls (g ∼ 0.88 and 95% confidence interval [0.65, 1.1], based on 13 studies; Mohammad et al., 2016).