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CONTACT JAX micetech@jax.org 1.800.422.6423 (US) 1.207.288.5845 (International) LEARN MORE ABOUT JAX MICE AND SERVICES JAX.ORG/JMCRS Frequently Asked Questions How do ES cells mitigate the effects of a gene that causes a severe phenotype? CRISPR modifications produce mosaic founder mice, often with multiple genetic variants. With ES cells, you can screen many clones to identify the ones that have only the intended modification. For example, if you are attempting to make a point mutation you can choose ES cell clones that have the mutation without any unintended knockout alleles that may cause a severe phenotype. Are the founder chimeric mice identified by coat color, or are they sequenced? Both. Chimeric mice are identified by coat color, but they are also sequenced with short-range and long-range sequencing techniques to ensure that the modification is intact and in the expected genomic location. What does it mean if an ES cell modification is not germline transmissible? Even if the microinjection is successful and produces founder mice, the genetic modification may not be germline transmissible. This will be evidenced when you breed the founder mice to a wild type strain, and the genetic modification is lost. If this occurs with all founder mice, then a second ES cell microinjection may need to be attempted. What is included in the free feasibility assessment? Each assessment may be different depending on the model, but JAX will identify suitable guide RNA(s) that target the region with low risk of off-target effects, assess risk of adverse phenotypes that may impact viability or fertility, and determine if the proposed design will meet the intended scientific goal. If complications are discovered, JAX will communicate the risks and discuss potential alternatives to mitigate risks. Will JAX provide a genotyping protocol for the mutation? JAX will provide primer sequences for you to use in your current genotyping platform, as well as sequencing if you would like to design your own primers. Can JAX provide homozygous mice? Yes, we can add on a custom breeding project to breed to homozygosity. We can also breed to other strains (a cre- expressing strain, for example) or produce experiment-ready cohorts. How do I initiate a new project? Your JAX sales representative will ask for additional details about the model that you would like to generate. Our study directors will then perform a feasibility assessment, and generate a Statement of Work (SOW), which will typically be provided to you within 1 week. If you would like to proceed, you must sign the SOW and provide a PO to initiate the project. Crispr/Cas9 In Es Cells Model Generation