Simmons Alexandra D, Carvalho Claudia M B, Lupski James R
Biology Department, University of St Thomas, Houston, TX, USA.
Methods Mol Biol. 2012;838:1-27. doi: 10.1007/978-1-61779-507-7_1.
The elucidation of genomic disorders began with molecular technologies that enabled detection of genomic changes which were (a) smaller than those resolved by traditional cytogenetics (less than 5 Mb) and (b) larger than what could be determined by conventional gel electrophoresis. Methods such as pulsed field gel electrophoresis (PFGE) and fluorescent in situ hybridization (FISH) could resolve such changes but were limited to locus-specific studies. The study of genomic disorders has rapidly advanced with the development of array-based techniques. These enabled examination of the entire human genome at a higher level of resolution, thus allowing elucidation of the basis of many new disorders, mechanisms that result in genomic changes that can result in copy number variation (CNV), and most importantly, a deeper understanding of the characteristics, features, and plasticity of our genome. In this chapter, we focus on the structural and architectural features of the genome, which can potentially result in genomic instability, delineate how mechanisms, such as NAHR, NHEJ, and FoSTeS/MMBIR lead to disease-causing rearrangements, and briefly describe the relationship between the leading methods presently used in studying genomic disorders. We end with a discussion on our new understanding about our genome including: the contribution of new mutation CNV to disease, the abundance of mosaicism, the extent of subtelomeric rearrangements, the frequency of de novo rearrangements associated with sporadic birth defects, the occurrence of balanced and unbalanced translocations, the increasing discovery of insertional translocations, the exploration of complex rearrangements and exonic CNVs. In the postgenomic era, our understanding of the genome has advanced very rapidly as the level of technical resolution has become higher. This leads to a greater understanding of the effects of rearrangements present both in healthy subjects and individuals with clinically relevant phenotypes.
基因组疾病的阐明始于分子技术，这些技术能够检测到基因组变化，这些变化(a) 比传统细胞遗传学所分辨的变化小（小于5 Mb），(b) 比传统凝胶电泳所能确定的变化大。脉冲场凝胶电泳（PFGE）和荧光原位杂交（FISH）等方法可以分辨此类变化，但仅限于位点特异性研究。随着基于阵列技术的发展，基因组疾病的研究迅速推进。这些技术能够以更高的分辨率检查整个人类基因组，从而得以阐明许多新疾病的基础、导致可引起拷贝数变异（CNV）的基因组变化的机制，最重要的是，更深入地了解我们基因组的特征、特性和可塑性。在本章中，我们重点关注基因组的结构和架构特征，这些特征可能导致基因组不稳定，描述诸如NAHR、NHEJ和FoSTeS/MMBIR等机制如何导致致病重排，并简要描述目前用于研究基因组疾病的主要方法之间的关系。我们最后讨论了我们对基因组的新认识，包括：新发突变CNV对疾病的贡献、嵌合体的丰度、亚端粒重排的程度、与散发性出生缺陷相关的新发重排的频率、平衡和不平衡易位的发生、插入性易位的不断发现、复杂重排和外显子CNV的探索。在后基因组时代，随着技术分辨率水平的提高，我们对基因组的理解迅速推进。这使我们对健康受试者和具有临床相关表型的个体中存在的重排效应有了更深入的了解。
