Checks and balancers: balancer chromosomes to facilitate genome annotation

Trends Genet. 2004 Jun;20(6):252-9. doi: 10.1016/j.tig.2004.04.004.


Phenotype-driven mutagenesis screens are used to discover gene function in model organisms. Mutations that are induced by chemical mutagens can occur anywhere in the genome. However, the use of a balancer chromosome (where a phenotypically marked segment of a chromosome is inverted) in a mutagenesis screen enables mutations to be mapped in a defined region of the genome and maintained stably in a heterozygous state. Mouse balancer chromosomes can be engineered using Cre-loxP technology in selected regions of the genome. Balancer mutagenesis screens will provide a systematic functional analysis of the genes on mouse chromosomes, and consequently, will facilitate a functional annotation of the mammalian genome sequence.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Chromosomes / drug effects
  • Chromosomes / genetics*
  • Genetic Engineering
  • Genome*
  • Humans
  • Mice
  • Mutagenesis / genetics*
  • Mutagens / pharmacology
  • Phenotype
  • Sequence Deletion


  • Mutagens