Genetically modified mice are an essential tool in research. The original background strain used to create the genetically modified mice can sometimes be inappropriate for a specific phenotypic analysis of the mutation. The transgene needs to be introduced to a more suitable genetic background. This can be done by marker assisted breeding, which means that a congenic strain can be generated in an accelerated fashion.

To create a congenic line it takes a minimum of 10 generations (backcrossing donor mice onto a recipient background to N10). At this point it is accepted that the gene of interest (allele) from the donor strain is then theoretically 99.9% identical to the recipient host inbred strain. In mice, this takes approximately 2–3 years to achieve.  Speed congenics is an attempt to cut this time in half.

Often mice are generated on a mixed or genetically undefined background. Knockin/knockout mice produced by homologous combination are often produced on a mixed background (generally a mix of C57BL/6 and 129). Transgenic mice produced by pronuclear injection can also be produced on a F1 or F2 background. These animals may not be on the appropriate genetic background for researchers.

Also, the use of a congenic strain in research has several advantages over analysis on an undefined/mixed genetic background. It provides a defined experimental model for characterization as all the mice are genetically identical. This reduces experimental variability and in turn reduces the total number of mice needed per experiment.

Backcrossing mice for 10 generations to produce heterozygous N10 mice and then intercrossing these mice to produce homozygous mice is traditionally the way of developing a congenic strain. This typically takes 2-3 years to complete. Using a marker assisted/speed congenics screening approach this timeframe can be halved. Single nucleotide polymorphism (SNP) analysis at each generation will be used in order to generate a congenic strain on the desired genetic background in five generations.

Although there is initially extra cost involved in screening these mice, there is an overall reduction in the cost of producing a new congenic strain. These savings can be considerable because of the reduced animal numbers and reduced agistment costs (because of the reduced number). Speed congenic technology might give you a congenic strain in 12 to 18 months versus 2 to 3 years and research can be completed sooner with the strain.

Please contact us to discuss your individual project and your requirements.

  • TASQ registration form must be completed prior to service commencement.

  • A current AEC certificate and OGTR number must be supplied prior to commencement of service.

  • Work performed by TASQ will be invoiced by TASQ.  AGRF will send their invoice direct to Client.

  • TASQ will not euthanase any WT or non breeding progeny/mice until written request from Client.