藏族人载脂蛋白B基因信号肽多态性与血脂水平

The polymorphism of apolipoprotein B signal peptide insertion/deletion and serum levels of lipoproteins in healthy Tibetan population

目的：了解正常藏族人群载脂蛋白Ｂ（ａｐｏＢ） 基因多态性及其血脂特点。方法：随机选取１００ 例正常成年藏族受试者，男女各半，年龄１８ ～６０ 岁。测定其血清甘油三脂（ＴＧ） 、总胆固醇（ＴＣ） 、低密度脂蛋白胆固醇（ＬＤＬ－ Ｃ） 、高密度脂蛋白胆固醇（ ＨＤＬ－ Ｃ） 、ａｐｏＡＩ、ａｐｏＢ 和脂蛋白（ａ）［Ｌｐ（ａ）］ 的浓度；并采用ＰＣＲ 方法检测其ａｐｏＢ 基因信号肽插入／缺失（ｉｎｓ／ｄｅｌ） ＤＮＡ 片段的多态性，计算各等位基因的分布频率。结果：藏族人群中以ｉｎｓ 等位基因分布为主（０－７４５） ，ｄｅｌ等位基因频率占０－２５５ ，两种等位基因分布无明显的性别差异。组成的三种基因型分别为ｉｎｓ／ｉｎｓ ５６ 例、ｉｎｓ／ｄｅｌ ３７ 例、ｄｅｌ／ｄｅｌ ７ 例。与汉族人群比较，藏族ｉｎｓ／ｄｅｌ 等位基因的频率与其相近，但ｄｅｌ 等位基因频率显著低于西方高加索人种（０－３４０ ，Ｐ＜ ０－０５） 。藏族人群中男女各年龄段（１８ ～３９ 岁、４０ ～６０ 岁） 的各项血脂指标变化不大，但ＴＣ、ＬＤＬ－ Ｃ 和ａｐｏＢ的含量显著低于汉族和西方人群，Ｌｐ（ａ） 的水平与后者接近。ｄｅｌ 等位基因的个体其ＬＤＬ－ Ｃ 的浓度高于ｉｎｓ 者。

AIM:To understand the apolipoprotein B (apoB)gene polymorphisms and lipoprotein natures of normal Tibetan population. METHODS:The serum levels of TG, TC, LDL-C, HDL-C, apoAI, apoB and Lp(a) were measured and the polymorphism at insertion (Ins)/deletion (Del) site of signal peptide in apolipoprotein B gene was studied by using PCR in 100 random normal individuals in Tibetan population respectively. RESULTS:Ins allele of Ins/Del polymorphism of the signal peptide was a common one with relative frequency of 0.745, while Del allele had the frequency of 0.255 in Tibetan people. There were not significant differences of two allele frequencies between Tibetan male and female groups. Three genotypes formed by two alleles were Ins/Ins 56, Ins/Del 37 and Del/Del 7, respectively. The relative frequencies of Ins/Del alleles were similar to that in Han nationality, but the frequency of Del allele significantly lower than one of western Caucasian population (0.340, P<0.05 ). No marked lipid differences were found among the various age groups in Tibetan male and female, the detected levels of TC, LDL-C and apoB, however, were significantly lower than those of Han and western populations. A significant association between Ins/Del polymorphism and serum LDL-C level was observed in the subjects of Tibetan.CONCLUSIONS:The data of serum lipids and polymorphism of apoB signal peptide insertion/deletion from normal Tibetan were obtained. The Del allele may be positively related to serum LDL-C levels in the population.