Dove William F, Shedlovsky Alexandra, Clipson Linda, Amos-Landgraf James M, Halberg Richard B, Krentz Kathleen J, Boehm Frederick J, Newton Michael A, Adams David J, Keane Thomas M
McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin 53706 Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53706
McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin 53706.
G3 (Bethesda). 2014 Apr 17;4(6):1113-21. doi: 10.1534/g3.114.010595.
A central goal in the analysis of complex traits is to identify genes that modify a phenotype. Modifiers of a cancer phenotype may act either intrinsically or extrinsically on the salient cell lineage. Germline point mutagenesis by ethylnitrosourea can provide alleles for a gene of interest that include loss-, gain-, or alteration-of-function. Unlike strain polymorphisms, point mutations with heterozygous quantitative phenotypes are detectable in both essential and nonessential genes and are unlinked from other variants that might confound their identification and analysis. This report analyzes strategies seeking quantitative mutational modifiers of Apc(Min) in the mouse. To identify a quantitative modifier of a phenotype of interest, a cluster of test progeny is needed. The cluster size can be increased as necessary for statistical significance if the founder is a male whose sperm is cryopreserved. A second critical element in this identification is a mapping panel free of polymorphic modifiers of the phenotype, to enable low-resolution mapping followed by targeted resequencing to identify the causative mutation. Here, we describe the development of a panel of six "isogenic mapping partner lines" for C57BL/6J, carrying single-nucleotide markers introduced by mutagenesis. One such derivative, B6.SNVg, shown to be phenotypically neutral in combination with Apc(Min), is an appropriate mapping partner to locate induced mutant modifiers of the Apc(Min) phenotype. The evolved strategy can complement four current major initiatives in the genetic analysis of complex systems: the Genome-wide Association Study; the Collaborative Cross; the Knockout Mouse Project; and The Cancer Genome Atlas.
复杂性状分析的一个核心目标是识别修饰表型的基因。癌症表型的修饰因子可能在显著的细胞谱系上发挥内在或外在作用。通过乙基亚硝基脲进行的生殖系点突变可以为感兴趣的基因提供包括功能丧失、功能获得或功能改变的等位基因。与品系多态性不同，具有杂合数量表型的点突变在必需基因和非必需基因中均可检测到，并且与可能混淆其鉴定和分析的其他变体不连锁。本报告分析了在小鼠中寻找Apc(Min)定量突变修饰因子的策略。为了识别感兴趣表型的定量修饰因子，需要一组测试后代。如果奠基者是精子被冷冻保存的雄性，则可以根据统计显著性的需要增加组群大小。这种鉴定中的第二个关键要素是一个没有表型多态性修饰因子的定位面板，以便进行低分辨率定位，随后进行靶向重测序以识别致病突变。在这里，我们描述了一组针对C57BL/6J的六个“同基因定位伙伴系”的开发，这些系携带通过诱变引入的单核苷酸标记。一种这样的衍生物B6.SNVg，已证明与Apc(Min)结合时在表型上是中性的，是定位Apc(Min)表型诱导突变修饰因子的合适定位伙伴。所发展的策略可以补充复杂系统遗传分析中当前的四项主要举措：全基因组关联研究；协作杂交；基因敲除小鼠项目；以及癌症基因组图谱。
