Subarachnoid haemorrhage or APOE ɛ4 possession separated low from medium or high probability groups (appendix), and had a sensitivity of 100% (95% CI 88–100; appendix) meaning that the absence of these two predictors with lobar intracerebral haemorrhage ruled out moderate or severe CAA. The gene discussed is APOE; the disease is subarachnoid hemorrhage.