Normolipidemic Dysbetalipoproteinemia (apo E-3 欠損症) の4例

Liporprotein lipids of four patients with normolipidemic dysbetalipoproteinemia (group-N) were compared with those of ten patients with primary type III hyperlipoproteinemia (group-H) and those of 24 normal subjects (group-C) with total cholesterol (TC) less than 230mg/dl, triglyceride (TG) less than 160mg/dl and positive apoE-3 or apoE-4.Serum TC levels of group-N (143±30, mean±SD, mg/dl) were significantly lower than those of group-H (388±150mg/dl) and group-C (174±26mg/dl). Group-N showed significantly higher VLDL-TC (32±12mg/dl) and IDL-TC (15±9mg/dl) levels, and significantly lower LDL-TC (36±14mg/dl) levels than group-C. In group-H, VLDL-TC (207±143mg/dl) and IDL-TC (51±21mg/dl) levels were much higher than in group-N, and LDL-TC levels (54±20mg/dl) were intermediary between those of group-N and group-C. Group-N had higher VLDL-TG and lower LDLTG levels than group-C.The ratio of VLDL-TC/TG was significantly different among group-H, group-N and group-C, 0.42±0.08, 0.29±0.05 and 0.16±0.06, respectively. The ratios of VLDL-TC/LDL-TC in group-H (5.73±7.40) and group-N (0.95±0.38) were significantly higher than in group-C (0.17±0.11). But there were only small differences in these two ratios between group-N and group-C. The ratios of IDL-TC/LDL-TC in group-H (1.02±0.5) and group-N (0.40±0.10) were higher than in group-C (0.07±0.03). The distribution of this ratio in group-N (from 0.30 to 0.52) was apparently higher than that in group-C (below 0.14).VLDL-TC and IDL-TC levels were positively correlated with serum TC levels in a patient (T.K.) with primary type III hyperlipoproteinemia, whose serum TC levels changed between 175 and 555mg/dl. The IDL-TC/LDL-TC ratio of this patient was much higher than normal range even when her serum TC level, VLDL-TC/LDL-TC ratio and VLDL-TC/TG ratio fell in the normal ranges.Conclusions: 1) Dysbetalipoproteinemia showed hypo-, normo- and hyperlipidemia. 2) In normolipidemic dysbetalipoproteinemia, VLDL- and IDL-cholesterol levels increased, LDL-cholesterol level decreased, and VLDL-TC/TG ratio elevated as in primary type III hyperlipoproteinemia due to the impaired VLDL metabolism and the accumulation of remnant lipoproteins caused by deficiency of apoE-3. 3) These patients may have higher risk for atherosclerosis than normal subjects with apo E-3 or apoE-4 because of accumulation of remnant lipoproteins.