Three of these paths included correlations: one between the symptoms of stress-related disorders (anxiety and depression) and two between the input variables (MECP2 and gender with the interaction term MECP2*gender), while the fourth path was a direct arc from gender to MECP2. The addition of these four paths significantly improved the model fit (significant likelihood ratio, p < 0.001). The gene discussed is MECP2; the disease is depressive disorder.