Genetic Quality Control And Stability Programs

Patented Genetic Stability Program (GSP)

Our patented JAX Genetic Stability Program (GSP) minimizes cumulative genetic drift, including that caused by copy number variation (CNV). We achieve this by regenerating our foundation stocks from cryopreserved, pedigreed embryos every five generations. This process ensures the maintenance of genetic integrity across mutant colonies. By regularly backcrossing these mutant colonies to our GSP inbred strains, we ensure their genetic backgrounds remain consistent with the parent inbred and other similarly maintained mutant strains.

The GSP, initiated in 2003 (Taft et al. 2006), is protected by patents issued in 2009 (US patent 7,592,501) and 2012 (US patent 8,110,721).

Inbred Strains Currently in the GSP Program

The JAX Genetic Quality Control (GQC) Program

Systematic Screens For Genotype Variations

Since phenotyping alone may not detect genetic contamination, we complement it with genotyping to perform several key functions:

• Verifying Genetic Background: Ensuring the accuracy of the genetic lineage
• Identifying Cloned Mutations: Detect specific genetic alterations in cloned strains
• Confirming Mutant Alleles: Validate presence of mutant alleles in genetically engineered strains
• Differentiating Genotypes: Distinguish between homozygous, heterozygous, and wild-type carriers in segregating mutant strains
• Tracking Allele Transfer: Identify mutant alleles that have been transferred to different genetic backgrounds

Our SNP Panel

We primarily use a specialized panel of over 2,000 SNP markers to verify genetic backgrounds and detect contamination. The panel, informative for 103 mouse strains, is used for genotyping all foundation stock breeders and randomly selected mice from expansion and production colonies for SNP genotyping at least annually. A subset of 52 markers is employed in 99% of our assays for routine quality control to verify the genetic background of all JAX® Mice strains.

The panel offers several key advantages:

• Reliable, straightforward, rapid, and cost-effective
• Compatible with high-throughput processing
• Suitable for both large- and small-scale animal facilities
• Enables genetic typing before mice are used as breeders

Other Assays That Ensure Genetic Consistency

Hemolytic Complement (Hc - formerly C5)

We utilize a hemolytic complement assay to differentiate between the congenic strains B10.D2-Hc¹ H2^d H2-T18^c/nSnJ (000463) and B10.D2-Hc⁰ H2^d H2-T18^c/oSnJ (000461). These two strains are identical across 23 isoenzymes, H2, Ea9, and our 27-marker SNP panel. The sole distinction between them lies in the Hc locus: B10.D2-Hc¹ H2^d H2-T18^c/nSnJ expresses the Hc antigen (Hc1), while B10.D2-Hc⁰ H2^d H2-T18^c/oSnJ does not express it (Hc0).

Major Histocompatibility Complex (MHC)

The H2 complex, the major histocompatibility complex (MHC) in mice, is critical in determining histocompatibility and influencing tissue acceptance or rejection in transplantation studies. The H2 haplotype serves as a valuable immunological marker, and in cases where congenic strains differ solely at their H2 loci, it may be the only method available for accurate strain typing.

Verification of Alleles in Engineered and Spontaneous Mutants

We employ a range of allele-specific genotyping techniques to ensure the verification of genetic variants in both engineered and spontaneous mutants. Our methods include standard polymerase chain reaction (PCR), quantitative PCR, melt curve analysis, endpoint sequencing, and pyrosequencing. We either follow established PCR protocols or develop customized ones to meet our needs. Our high-throughput genotyping laboratory efficiently processes over a thousand samples daily, ensuring robust and reliable results.

Isozymes

Isozymes are different forms of the same protein that vary in characteristics, such as electrophoretic mobility or enzymatic activity. These isoenzymes are often present in multiple tissues and can be detected in plasma or red blood cell lysates. Due to their strain-specific expression, isozymes serve as valuable biochemical markers.

While isozyme typing is quick, straightforward, reproducible, and cost-effective, it cannot always be performed on live mice. This limitation means that only retired breeders can be genotyped using isozyme assays, which can delay the detection of genetic contamination. Consequently, we generally use isozyme assays only when our SNP panel is insufficient for distinguishing between strains. For instance, we employ isozyme assays to genotype mice for Esterase 1 (Es1e), Esterase 9 (Es9), or Glucose Phosphate Isomerase 1 (Gpi1) alleles.