Averna M, Seip R L, Mankowitz K, Schonfeld G
Division of Atherosclerosis, Nutrition, and Lipid Research, Washington University School of Medicine, St. Louis, MO 63110.
J Lipid Res. 1993 Nov;34(11):1957-67.
Hypobetalipoproteinemia in many kindreds is associated with truncated forms of apoB-100. Mutations of the apoB gene specifying more than 20 different carboxyl terminal truncations of apoB have been identified ranging in length from apoB-2 to apoB-89. Truncations longer than apoB-48 appear to be secreted only by liver, while truncations shorter than apoB-48 are secreted by liver as well as intestine. Thus, intestines of subjects heterozygous for truncations > apoB-48 contain two alleles producing apoB-48, while intestines of heterozygotes with truncations < apoB-48 contain only one allele producing apoB-48. Our aims were to assess whether intestinal fat absorption differed from normal in subjects with apoB-truncation-associated hypobetalipoproteinemia and whether fat absorption in heterozygotes with apoB < 48 differed from heterozygotes with apoB > 48. Ten subjects heterozygous for apoB > 48 (apoBs -89, -75, -54, -52), six heterozygous for apoB < 48 (apoBs -46, -40, -31) and a group of 16 controls matched for age, sex, body mass index characteristics, and eating similar diets were given identical fat meals containing vitamin A. Plasma triglycerides in whole plasma and retinyl palmitate in chylomicron and non-chylomicron (remnant) fractions were analyzed at zero time and over the next 14 hours. Fasting vitamins A and E also were quantified. Fasting plasma levels of vitamin E were lower in heterozygotes (536 +/- 198 mg/l for apoB > 48 vs. 372 +/- 155 for apoB < 48) versus controls (1162 +/- 441), but were not different when corrected for differences in LDL-C. Plasma vitamin A levels (uncorrected) were not different. Meal responses were characterized in terms of peak concentrations and areas under the curves (after subtraction of minimum points). These indices of fat absorption were comparable in all apoB phenotype groups suggesting that one allele specifying the intestinal production of apoB-48 is sufficient for normal fat absorption.
许多家族性低β脂蛋白血症与截短形式的载脂蛋白B-100相关。已鉴定出载脂蛋白B基因的突变，这些突变导致载脂蛋白B出现20多种不同的羧基末端截短，长度范围从载脂蛋白B-2到载脂蛋白B-89。长于载脂蛋白B-48的截短形式似乎仅由肝脏分泌，而短于载脂蛋白B-48的截短形式则由肝脏和肠道分泌。因此，截短形式>载脂蛋白B-48的杂合子受试者的肠道含有两个产生载脂蛋白B-48的等位基因，而截短形式<载脂蛋白B-48的杂合子的肠道仅含有一个产生载脂蛋白B-48的等位基因。我们的目的是评估载脂蛋白B截短相关低β脂蛋白血症患者的肠道脂肪吸收是否与正常情况不同，以及载脂蛋白B<48的杂合子与载脂蛋白B>48的杂合子的脂肪吸收是否不同。10名载脂蛋白B>48的杂合子受试者（载脂蛋白B分别为-89、-75、-54、-52）、6名载脂蛋白B<48的杂合子受试者（载脂蛋白B分别为-46、-40、-31）以及一组16名年龄、性别、体重指数特征匹配且饮食相似的对照组，均给予含有维生素A的相同脂肪餐。在0时及接下来的14小时内分析全血浆中的血浆甘油三酯以及乳糜微粒和非乳糜微粒（残余物）部分中的视黄醇棕榈酸酯。还对空腹时的维生素A和E进行了定量。与对照组（1162±441）相比，杂合子空腹血浆维生素E水平较低（载脂蛋白B>48者为536±198mg/l，载脂蛋白B<48者为372±155mg/l），但校正低密度脂蛋白胆固醇差异后并无不同。血浆维生素A水平（未校正）无差异。根据峰值浓度和曲线下面积（减去最低点后）来表征餐食反应。所有载脂蛋白B表型组的这些脂肪吸收指标具有可比性，这表明一个决定肠道产生载脂蛋白B-48的等位基因足以实现正常的脂肪吸收。
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