In our study, we used a systematically acquired brain tissue bank nested within a prospective, population-based cohort study to develop and internally validate a simple, three-variable model using two CT features (subarachnoid haemorrhage and finger-like projections from intracerebral haemorrhage) and APOE genotype to predict moderate or severe CAA associated with lobar intracerebral haemorrhage. The gene discussed is APOE; the disease is subarachnoid hemorrhage.