JAK2 V617F mouse PCR genotyping detection is a molecular diagnostic assay designed to identify the JAK2 V617F point mutation in genetically engineered mouse models used for myeloproliferative neoplasm research. This PCR-based test accurately distinguishes wild-type, heterozygous, and homozygous mutant genotypes, providing essential quality control for colony breeding and experimental design. With high sensitivity, fast turnaround, and reliable allele discrimination, it is an indispensable tool for laboratories working with JAK2 V617F knock-in and conditional expression mouse lines.
Technical Overview
The Janus kinase 2 (JAK2) gene encodes a non-receptor tyrosine kinase that plays a central role in cytokine receptor signaling and normal hematopoiesis. The V617F mutation is a guanine-to-thymine (G to T) substitution at nucleotide 1849 within exon 14 of the JAK2 gene, resulting in a valine-to-phenylalanine amino acid change at codon 617. This gain-of-function mutation abrogates the autoinhibitory function of the JH2 pseudokinase domain, leading to constitutive activation of the JAK-STAT signaling pathway.
In human medicine, the JAK2 V617F mutation is the hallmark molecular lesion of Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), present in more than 95 percent of polycythemia vera cases and approximately 50 to 60 percent of essential thrombocythemia and primary myelofibrosis cases. Genetically engineered mice carrying the V617F mutation, including knock-in models expressing the mutant allele at the endogenous locus, faithfully recapitulate key features of human MPNs, including erythrocytosis, leukocytosis, splenomegaly, and bone marrow fibrosis.
PCR-based genotyping is required to confirm the genetic status of every animal before it enters a breeding program or experimental study. Reliable genotype identification prevents mislabeled animals, clarifies zygosity in breeding colonies, and ensures that experimental groups are correctly assigned, thereby safeguarding the reproducibility of research data.
Testing Samples
The assay accepts a variety of biological materials collected from live animals or necropsy specimens. All samples should be collected using clean, nuclease-free tools to avoid cross-contamination between animals.
Tail Tissue Biopsy
A 1 to 2 mm tail tip snip collected from pups at 10 to 21 days of age is the most widely used sample type. Tail tissue yields high-quality genomic DNA suitable for multiple downstream assays and is the standard for routine colony genotyping.
Ear Punch Biopsy
A 2 mm ear punch biopsy can serve the dual purpose of animal identification and DNA source. Ear punches are particularly convenient for adult mice already enrolled in identification numbering systems and reduce the need for additional invasive procedures.
Blood Samples
Small volumes of peripheral blood, typically 20 to 50 microliters obtained from the tail vein or submandibular vein, can be used for genotyping when tissue collection is impractical. Blood-based protocols include an erythrocyte lysis step before DNA extraction.
Organ and Other Tissue Samples
Spleen, bone marrow, ear, toe clips, or snap-frozen organ fragments collected at necropsy are also acceptable. Fresh or frozen tissues should be shipped on ice or dry ice, respectively, and fixed tissues should be avoided unless specifically validated.
Testing Items
The service provides comprehensive analysis of the JAK2 locus covering the following deliverables:
- Wild-type allele detection: amplification of the native JAK2 exon 14 sequence to confirm the presence of the endogenous allele.
- Mutant V617F allele detection: specific amplification or probe-based discrimination of the V617F mutant sequence, including detection of conditional knock-in cassettes where applicable.
- Genotype determination: clear assignment of each animal as homozygous wild-type (WT/WT), heterozygous (WT/V617F), or homozygous mutant (V617F/V617F).
- Internal control amplification: verification of DNA quality and PCR performance using a control primer pair to rule out false-negative results.
- Electropherogram and gel documentation: provision of raw gel images, chromatograms, or amplification plots together with a written interpretation for full data traceability.
Testing Methods
The workflow integrates well-established molecular biology techniques optimized for high-throughput mouse genotyping. Each method can be selected independently or in combination depending on the required level of resolution.
Genomic DNA Extraction
Genomic DNA is isolated from biopsy material using either rapid alkaline lysis for same-day PCR or silica column and magnetic bead-based purification when higher DNA purity is required. DNA concentration and purity are assessed by spectrophotometry to ensure amplifiable template quality.
Conventional End-Point PCR
Panels of primers flanking the mutated region of exon 14 are used to amplify wild-type and mutant alleles. Amplification products are resolved on 2 to 3 percent agarose gels, and genotype is assigned based on the expected band sizes for each allele.
Allele-Specific PCR
allele-specific strategy employs primers whose 3-prime terminus matches either the wild-type guanine or the mutant thymine at position 1849. Under stringent annealing conditions, amplification occurs only when the primer perfectly matches the template, allowing direct allele discrimination in a single reaction.
PCR-Restriction Fragment Length Polymorphism Analysis
The V617F substitution alters a recognition site for certain restriction endonucleases. Following PCR amplification, digestion with an appropriate enzyme produces distinct fragment patterns for wild-type and mutant alleles, enabling heterozygotes to be identified by the presence of both digested and undigested bands.
Sanger Sequencing Confirmation
Amplicons covering codon 617 can be subjected to Sanger sequencing for definitive confirmation. Sequencing is recommended for founder animal validation, resolution of ambiguous gel patterns, and verification of novel or conditional alleles.
Quantitative Real-Time PCR
TaqMan or SYBR Green based qPCR assays with allele-specific hydrolysis probes offer closed-tube detection, minimizing contamination risk. This approach provides semi-quantitative estimation of mutant allele burden, which is valuable for monitoring chimerism or mosaic expression in conditional models.
Applications
JAK2 V617F genotyping services support a broad range of preclinical and basic research applications:
- Myeloproliferative neoplasm modeling: genotype confirmation for mice used in studies of polycythemia vera, essential thrombocythemia, and primary myelofibrosis.
- Colony management: routine screening of breeding pairs and offspring to maintain line integrity and track Mendelian inheritance ratios.
- Drug development: enrollment genotyping for preclinical trials evaluating JAK inhibitors such as ruxolitinib and fedratinib, as well as novel pathway-targeted therapies.
- Hematopoiesis research: correct assignment of experimental animals in studies of cytokine signaling, erythropoiesis, thrombopoiesis, and stem cell biology.
- Inflammation and thrombosis studies: supporting research into the systemic consequences of constitutive JAK-STAT activation, including vascular inflammation and platelet-mediated thrombotic events.
- Transplantation and chimerism experiments: quantifying mutant allele contribution in competitive repopulation and bone marrow transfer experiments.
FAQ
Question: How sensitive is the PCR assay for detecting the V617F allele?
Answer: Optimized allele-specific PCR and qPCR assays can reliably detect the mutant allele at a sensitivity of approximately 1 to 5 percent mutant-to-wild-type DNA ratio, which is sufficient for standard germline genotyping and most mosaic analysis applications.
Question: What is the typical turnaround time?
Answer: Standard genotyping results are generally delivered within 2 to 4 working days after sample receipt. Sequencing confirmation extends the turnaround to approximately 5 to 7 working days.
Question: Can the test distinguish heterozygous from homozygous mutant animals?
Answer: Yes. The combined interpretation of wild-type and mutant allele amplification patterns, optionally confirmed by sequencing, allows unambiguous determination of zygosity for breeding and experimental grouping.
Question: How should samples be stored and shipped?
Answer: Fresh tissue samples can be shipped on ice packs for arrival within 48 hours. For longer transit, samples should be frozen and shipped on dry ice. Alternatively, tissues preserved in 95 percent ethanol at a minimum 3:1 reagent-to-tissue ratio are acceptable for most PCR applications.
Question: What controls are included to guarantee result accuracy?
Answer: Each run includes known wild-type and known mutant positive control DNA, a no-template negative control, and an internal amplification control, ensuring that both false-positive and false-negative results are systematically excluded.
Question: Is the assay applicable to conditional JAK2 V617F models?
Answer: Yes. Primer panels can be customized to detect floxed alleles, Cre-mediated recombination events, and transgene-specific constructs, providing complete genotyping coverage for conditional and inducible JAK2 V617F mouse lines.