Detecting and Avoiding Problems When Using the Cre-lox System

Trends Genet. 2018 May;34(5):333-340. doi: 10.1016/j.tig.2017.12.008. Epub 2018 Jan 11.


The Cre-lox recombination approach is commonly used to generate cell-specific gene inactivation (or activation). We have noticed that the breeding and genotyping sections of papers utilizing Cre-lox techniques are frequently incomplete. While seemingly straightforward, there are important considerations that need to be implemented in the breeding and genotyping methods to prevent the introduction of experimental confounds. Germline recombination and transient expression of Cre recombinase during development are some examples of the complications that can occur, and conventional genotyping methods may fail to identify these events. In this opinion article, we highlight the importance of testing for unexpected recombination events, suggest strategies to isolate and minimize adverse recombination events, and encourage editors and reviewers to expect more definitive statements regarding the validation of genotyping.

Keywords: Cre recombinase; ectopic gene expression; germline recombination; transgenic mice.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Embryonic Development / genetics*
  • Gene Expression Regulation, Developmental / genetics
  • Germ Cells / growth & development
  • Integrases / genetics*
  • Mice
  • Mice, Transgenic / genetics
  • Recombination, Genetic*


  • Cre recombinase
  • Integrases