Since the apolipoprotein E gene (APOE) alleles are the major genetic risk for AD18 and CSF apolipoprotein E protein (ApoE) levels are associated with Aβ1-42 (refs 19, 20) and tau20, 21, we re-built the model to include CSF ApoE levels. The gene discussed is APOE; the disease is Alzheimer disease 18.