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G3 (Bethesda). 2014 Apr 17;4(6):1113-21. doi: 10.1534/g3.114.010595.

A strategy to identify dominant point mutant modifiers of a quantitative trait.

Author information

1
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 dove@oncology.wisc.edu.
2
McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin 53706.
3
Department of Statistics, University of Wisconsin-Madison, Madison, Wisconsin 53706.
4
Department of Statistics, University of Wisconsin-Madison, Madison, Wisconsin 53706 Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, Wisconsin 53706.
5
Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK.

Abstract

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.

KEYWORDS:

ENU mutagenesis; genetic modifiers; intestinal neoplasia; isogenicity

PMID:
24747760
PMCID:
PMC4065254
DOI:
10.1534/g3.114.010595
[Indexed for MEDLINE]
Free PMC Article

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