Racial/ethnic variation of APOE alleles for lobar intracerebral hemorrhage.

Abstract

APOE ε2 and ε4 alleles have been associated with lobar intracerebral hemorrhage (ICH) in predominately white populations; we sought to evaluate whether this held true among black and Hispanic populations. The Ethnic/Racial Variations of Intracerebral Hemorrhage study is a prospective, multicenter case-control study of ICH among white, black, and Hispanic participants. Controls were recruited to match cases based on age, ethnicity/race, sex, and geographic location. APOE genotyping and ICH location was determined blinded to clinical data. There were 907 cases of lobar ICH and 2,660 controls with APOE results. Both APOE ε2 (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.1-2.0, p = 0.01) and APOE ε4 (OR 2.0, 95% CI 1.5-2.6, p < 1 × 10-4) were associated with lobar ICH among white participants. Among black participants, neither APOE ε2 (OR 1.0, 95% CI 0.7-1.5, p = 0.97) nor APOE ε4 (OR 1.0, 95% CI 0.7-1.4, p = 0.90) were independent risk factors for lobar ICH. Similarly, among Hispanic participants, neither APOE ε2 (OR 1.0, 95% CI 0.6-1.8, p = 0.89) nor APOE ε4 (OR 1.2, 95% CI 0.8-1.7, p = 0.36) were associated with lobar ICH. Hypertension was a significant risk factor for lobar ICH in all 3 racial/ethnic groups. In contrast to Caucasian patients, in which amyloid risk factors predominate in lobar ICH, we found that hypertension was the predominant risk factor for lobar ICH. While APOE alleles are a risk factor for lobar ICH in white patients, they appear to have a much lower effect in lobar ICH in African American and Hispanic American populations. This suggests APOE ε2 and APOE ε4 do not affect lobar ICH risk homogeneously across ethnic populations. In addition, hypertension has a prominent role in lobar ICH risk, particularly among minorities.