短串联重复序列(STR)是人类基因组中一类丰富的结构或功能元件,并且在人类群体中表现出重复长度和遗传变异的多态性性质。有趣的是,STR扩张是约60种神经系统疾病的基础。然而,“口吃”伪影或噪音使研究STR扩张的发病机理变得困难。这里,我们以富含GC的CAG和富含AT的ATTCT串联重复序列为例，系统地研究了培养的人体细胞中的STR不稳定性。我们发现，在适当条件下进行PCR扩增的一式三份双向Sanger测序可以可靠地评估STR长度。此外,我们发现,双端读取双向覆盖STR区的下一代测序可以准确可靠地测定STR长度.最后,我们发现STR在培养的人细胞群中和在单细胞克隆过程中本质上是不稳定的.我们的数据表明了一种准确可靠地评估STR长度的通用方法，并且对研究STR扩展疾病的发病机理具有重要意义。
Short tandem repeats (STRs) are a class of abundant structural or functional elements in the human genome and exhibit a polymorphic nature of repeat length and genetic variation within human populations. Interestingly, STR expansions underlie about 60 neurological disorders. However, \"stutter\" artifacts or noises render it difficult to investigate the pathogenesis of STR expansions. Here, we systematically investigated STR instability in cultured human cells using GC-rich CAG and AT-rich ATTCT tandem repeats as examples. We found that triplicate bidirectional Sanger sequencing with PCR amplification under proper conditions can reliably assess STR length. In addition, we found that next-generation sequencing with paired-end reads bidirectionally covering STR regions can accurately and reliably assay STR length. Finally, we found that STRs are intrinsically unstable in cultured human cell populations and during single-cell cloning. Our data suggest a general method for accurately and reliably assessing STR length and have important implications in investigating pathogenesis of STR expansion diseases.
