Current evidence strongly suggests that that the Hb links all three dimensions of these disorders, including major depressive disorders, and anxiety disorders (internalizing) (Cui et al., 2018; Kang et al., 2018), substance use disorders (externalizing) (McLaughlin et al., 2017), and bipolar disorders and schizophrenia (psychotic experiences) (Figure 6B; Zhang C. et al., 2019; Wang Y. et al., 2020). The gene discussed is GSTM1; the disease is anxiety disorder.