Besides the causal relationships between psychiatric disorders (ADHD and SCZ in particular) and smoking, which had already been identified by previous works focused on substance abuse (Treur et al., 2021), we identify some preliminary transdiagnostic evidence of the causal involvement of CRP levels in the pathophysiology of late-onset BD and SCZ, that warrants additional research, as mentioned above. The gene discussed is CRP; the disease is psychiatric disorder.