In the multivariate regression analysis, other variables were positively associated with the severity of depression: the HOMA-IR (β = 0.0293, SE = 0.125, p = 0.019), PCSK9 (β = 0.0007, SE = 0.0003, p = 0.0159) and platelet count (β = 0.0017, SE = 0.0005, p = 0.0018) were positively associated with the severity of depression (BDI-II score) (Table 2). The gene discussed is PCSK9; the disease is major depressive disorder.