MIIDA, T. Apolipoprotein E Phenotypes in Patients with Coronary Artery Disease. Tohoku. J. Exp. Med., 1990, 160 (3), 177-187-The relationship between apolipoprotein E (Apo E) phenotypes and progression of coronary atheros-clerosis was investigated in 125 patients with coronary artery disease (CAD) proven angiographically (101 males, 24 females). To elucidate the pure effect of Apo E phenotypes on lipoproteins and coronary atherosclerosis, patients with familial hypercholesterolemia were excluded from the subjects. As a control group, 129 norml healthy volunteers (84 males, 45 females) were studied. In the CAD group, VLDL and LDL levels increased and HDL level decreased regardless of Apo E phenotypes in both sexes. The incidence of E4 was higher and that of E2 was slightly lower in the CAD group than in the control group. Two patients with E5/3 who had high LDL-cholesterol levels were found in the male CAD group. LDL-cholesterol level in E3/2 was lower than in E4/3 and E3/3 in the male CAD group. VLDL-cholesterol/triglyceride and VLDL cholesterol/phospholipid ratios in E3/2 were significantly higher than in E4/3 and E3/3 in the male CAD group, but the difference was not so marked as found in typical type III hyperlipidemia. When the male patients with effort angina were examined, coronary score (index of the severity of CAD) was the lowest in E3/2. In addition, the mean age at the onset of CAD was significantly higher in E3/2 than in E4/3. In conclusion, E2 acts protectively against coronary atherosclerosis, while E4 promotes it through the modulation of LDL-cholesterol level.