Genealogy of the 129 inbred strains: 129/SvJ is a contaminated inbred strain

Mamm Genome. 1997 Jun;8(6):390-3. doi: 10.1007/s003359900453.


The 129 mouse is the most widely used strain in gene targeting experiments. However, numerous substrains exist with demonstrable physiological differences. In this study a set of simple sequence length polymorphisms (SSLPs) was used to determine the relatedness of selected 129 substrains. 129/SvJ was significantly different from the other 129 substrains and is more accurately classified as a recombinant congenic strain (129cX/Sv), being derived from 129/Sv and an unknown strain. This mixed genetic background could complicate gene targeting experiments by reducing homologous recombination efficiency when constructs and ES cells are not derived from the same 129 substrain. Additionally, discrepancies due to different genetic backgrounds may arise when comparing phenotypes of genes targeted in different 129-derived ES cell lines.

Publication types

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

MeSH terms

  • Agouti Signaling Protein
  • Animals
  • Chromosome Mapping
  • Heterozygote*
  • Intercellular Signaling Peptides and Proteins*
  • Mice
  • Mice, Inbred C3H
  • Mice, Inbred Strains / genetics*
  • Phenotype
  • Polymorphism, Genetic*
  • Proteins / genetics
  • Recombination, Genetic
  • Stem Cells / physiology


  • Agouti Signaling Protein
  • Intercellular Signaling Peptides and Proteins
  • Proteins