HIGH-FREQUENCY OF APOLIPOPROTEIN-E EPSILON-2 ALLELE IN HEMORRHAGE DUETO CEREBRAL AMYLOID ANGIOPATHY

From the somewhat conflicting published data on apolipoprotein E (apoE ) genotype in hemorrhage due to cerebral amyloid angiopathy (CAA), it is unclear whether apoE genotype influences the risk of CAA-related he morrhage independently of its association with concomitant Alzheimer's disease (AD). We determined the apoE genotypes of 36 patients present ing with cerebral hemorrhage associated with histologically confirmed CAA. The frequency of apoE epsilon 2 was 0.25 and the frequency of apo E epsilon 4 was 0.18. Patients with CAA-related hemorrhage and concomi tant AD pathology (CERAD criteria, n = 17) had a high apoE epsilon 4 f requency, close to that in AD cases without hemorrhage. Patients in wh om CAA-related hemorrhage occurred in the absence of significant AD pa thology (n = 13) had an apoE epsilon 4 frequency somewhat lower than n on-AD controls without hemorrhage. However, in CAA-related hemorrhage, the apoE epsilon 2 frequency was high regardless of whether significa nt AD pathology was present. We conclude that whereas possession of ap oE epsilon 2 may be a risk factor for cerebral hemorrhage due to CAA, apoE epsilon 4 is a risk factor for concomitant AD but not an independ ent risk factor for CAA-related hemorrhage.