Important risk factors for the development of symptomatic ARIA include immunotherapy dose, APOE ε4 allele status, and baseline number of cerebral microbleeds, with higher doses and/or faster up-titration of antibody and two copies of the APOE ε4 allele associated with increased incidence of ARIA.1 We did not find a relationship between haemorrhagic lesions and APOE ε4 status in the current study, which may be because all iAD cases had at least one allele as well as the modest sample size. The gene discussed is APOE; the disease is cerebral microbleeds.