Abstract
The composition of apolipoprotein C and E isoforms of human triglyceride-rich lipoproteins appears to be related to the metabolism of hypertriglyceridemia. We analysed the heterogeneity of apo E in very low density lipoprotein from 25 hypertriglyceridemic patients, 38 patients with diabetes mellitus, and 23 patients with ischemic heart disease. The apo E2/E3 ratio in diabetics and in patients with ischemic heart disease tended to be higher than in controls. The incidence of variant pattern with apo E4 was higher in those patients than in controls. In this study, a new series of apo E components, apo E-7, was found in three patients with hyperlipidemia. All of three patients had the phenotype E 3/7. The first case, a 68-year-old man, had ischemic heart disease. The concentration of serum cholesterol and triglyceride was 202 and 312mg/dl, respectively and not responded to dietary restriction. The agar gel electrophoretic pattern of lipoproteins demonstrated broad beta band. The values for the cholesterol in VLDL, VLDL-cholesterol to VLDL-TG ratio, and VLDL-cholesterol to total triglyceride ratio were 43 mg/dl, 0.23, and 0.14, respectively, and were not compatible with the laboratory diagnostic criteria of type III hyperlipoproteinemia. Two brothers had also apo E-7 with hypertriglyceridemia. The second case, a 52-year-old male, had a history of hypertension. The serum cholesterol and TG levels were 281 and 511mg/dl, respectively (Type IV). The third case, a 47-year-old male, had mild diabetes mellitus. The serum cholesterol and TG levels were 223 and 224mg/dl, respectively. Apo VLDL from his mother and father revealed phenotype E 3/2 and E 4/2, respec-tively. These results suggest that the mutant apo E-7 may be related to the development of hyperlipidemia and atherosclerosis. Detailed structural and functional analyses of these mutant apo E are remained to be elucidated.
