APOE and early-onset autosomal dominant Alzheimer disease: This study demonstrated that APOE ε4, the most significant genetic risk factor for Alzheimer's disease and also a risk factor for IHD [8], worsens lipid and lipoprotein profiles (e.g., APOE ε4 is associated with elevated LDL-C, lower HDL—C, elevated ApoB, and lower ApoA-I).