INVESTIGATION OF DNA MICROSATELLITE REPEAT INSTABILITY AT THE FRIEDREICH ATAXIA

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。弗里德赖希共济失调是最常见的遗传性共济失调。其临床特征为进行性共济失调（不协调）、心肌病和糖尿病。它是由一种不寻常的DNA突变引起的，这种突变涉及FRDA基因中的GAA三联体重复（GAA-TR）序列从30个正常大小扩展到100-1700个三联体。扩展等位基因的长度决定了临床表现的严重程度。我们的目标是了解是什么使GAA-TR不稳定，并在患者的体细胞中逆转它作为一种潜在的治疗策略。使用一种新的技术，允许检测重复长度在单个细胞中，我们最近发现，GAA-TR序列显示体细胞不稳定性与显着程度的细胞间和组织特异性的变异性，我们假设，这种不稳定性是通过错误的DNA复制诱导。在这里，我们建议测试这一假设在模拟数学建模的复杂的数据集在我们的实验中产生的各种组织从几个人类受试者。我们将应用广泛的马尔可夫链模型来分析在体内观察到的不稳定性模式，并根据DNA复制的生物学构建现实的模型，并将其与微卫星DNA不稳定性的标准模型进行比较。我们相信，这将使我们实验验证的假设，调查GAA-TR不稳定的分子病因。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Friedreich ataxia is the most common inherited ataxia. It is characterized clinically by progressive ataxia (incoordination), cardiomyopathy and diabetes. It is caused by an unusual DNA mutation, which involves the expansion of a GAA triplet-repeat (GAA-TR) sequence in the FRDA gene from a normal size of 30 to 100-1700 triplets. The length of the expanded allele determines the severity of the clinical presentation. Our goal is to understand what makes the GAA-TR unstable and to reverse it in somatic cells from patients as a potential therapeutic strategy. Using a novel technique that allows the detection of repeat lengths in individual cells, we recently discovered that the GAA-TR sequence displays somatic instability with a remarkable degree of cell-to-cell and tissue-specific variability, and we hypothesized that this instability is induced via erroneous DNA replication. Here we propose to test this hypothesis in simulation by mathematically modeling the complex data set generated in our experiments using various tissues isolated from several human subjects. We will apply a broad family of Markov chain models to analyze the pattern of instability observed in vivo and to construct realistic models based on the biology of DNA replication and test them in comparison to standard models of microsatellite DNA instability. We believe that this will lead us to experimentally testable hypotheses to investigate the molecular etiology of GAA-TR instability.