Boerwinkle E, Xiong W J, Fourest E, Chan L
Center for Demographic and Population Genetics, University of Texas Health Science Center, Houston 77225.
Proc Natl Acad Sci U S A. 1989 Jan;86(1):212-6. doi: 10.1073/pnas.86.1.212.
The 3' flanking region of the apolipoprotein B (apoB) gene contains a hypervariable region consisting of a variable number of tandemly repeated short A + T-rich DNA sequences (VNTRs). We present a general method that utilizes the polymerase chain reaction to rapidly and accurately type this and other VNTR loci. We use tailored oligonucleotides and thermostable Taq polymerase to amplify the targeted region. The amplification products are directly visualized after agarose gel electrophoresis. Twelve alleles were readily identified in a sample of 125 unrelated individuals. The alleles differ with respect to the length of the amplified gene region. This genetic variability is inherited in an autosomal codominant manner. DNA sequence data indicate that individual alleles differ in the number of repeat units and the sensitivity of the technique is such that alleles differing in length by only 32 base pairs are readily distinguishable. A system of nomenclature based on the number of repeat units is suggested; an allele containing 37 repeat units is designated 3' beta 37, one containing 35 units is 3' beta 35, and so on. The frequency distribution of the 12 apoB VNTR alleles is bimodal with peaks at 37 and 47 repeat units and a nadir near 43 repeat units. We estimate that the 3' apoB VNTR locus has a heterozygosity index of 0.75 and a polymorphic information content of 0.73. It is a highly informative marker for genetic linkage studies on chromosome 2 and clinical and epidemiological studies involving the apoB gene. The high sensitivity and inexpensive nature of this technique make it superior to traditional Southern blot analysis for typing the 3' apoB VNTR. The method described is also directly applicable for rapid typing of other VNTRs in the human genome.
载脂蛋白B（apoB）基因的3'侧翼区域包含一个高变区，该区域由可变数量的串联重复短A+T丰富DNA序列（VNTR）组成。我们提出了一种通用方法，利用聚合酶链反应快速准确地对该VNTR位点及其他位点进行分型。我们使用定制的寡核苷酸和热稳定的Taq聚合酶扩增目标区域。扩增产物在琼脂糖凝胶电泳后直接可视化。在125名无关个体的样本中很容易鉴定出12个等位基因。这些等位基因在扩增基因区域的长度方面存在差异。这种遗传变异性以常染色体共显性方式遗传。DNA序列数据表明，各个等位基因在重复单元数量上存在差异，并且该技术的灵敏度使得长度仅相差32个碱基对的等位基因很容易区分。建议基于重复单元数量建立一种命名系统；含有37个重复单元的等位基因命名为3'β37，含有35个单元的命名为3'β35，依此类推。12个apoB VNTR等位基因的频率分布呈双峰型，在37和47个重复单元处出现峰值，在43个重复单元附近出现最低点。我们估计3' apoB VNTR位点的杂合度指数为0.75，多态信息含量为0.73。它是用于2号染色体遗传连锁研究以及涉及apoB基因的临床和流行病学研究的高信息性标记。该技术的高灵敏度和低成本特性使其在对3' apoB VNTR进行分型时优于传统的Southern印迹分析。所描述的方法也可直接用于快速分型人类基因组中的其他VNTR。
