The authors examined whether the APOE-epsilon4 allele is associated with an
earlier age at onset of AD in 71 African American patients with probable A
D. The authors found a linear dose effect in which each copy of the epsilon
4 allele was associated with a 3.6-year earlier onset of AD, indicating a d
ose-dependent relationship between APOE-epsilon4 and age at onset of AD in
African Americans.