AtlasGene
JAK2
Janus kinase 2
- HGNC 6192↗(opens in a new tab)
- Ensembl gene ENSG00000096968↗(opens in a new tab)
- NCBI Gene 3717↗(opens in a new tab)
Summary
- Cytogenetic location
- 9p24.1
- Coordinates
- Chromosome 9: 4,985,272–5,129,948 (GRCh38)
- Exons
- 25 exons across 144.7 kb
- Protein
- 1,132 amino acids, 130.7 kDa
- Also known as
- JTK10
- MANE Select transcript
- ENST00000381652.4NM_004972.4
- Locus type
- Protein-coding
- Very high
- Confident
- Low
- Very low
AtlasShare this page
This page as data
Add .json to the page's address, or ask for application/json, to read it as JSON.
library(jsonlite)
url <- "https://dantelabs.com/genes/jak2.json"
page <- fromJSON(url)
page$gene$nameRead JAK2, and the rest of your genome, with one test.
From $449Free shipping · Results in 6–8 weeks
Get my Genome TestCurated report relevant to this gene
Hereditary Thrombocythaemia (JAK2)
- Thrombocythaemia 3Autosomal dominant
Caused by an inherited change in JAK2, which makes a signalling protein that controls blood cell production. The reported changes lie in the parts of the protein that control its activity and make it more active, which raises platelet production. The first described, JAK2 R564Q, was found in a family with dominantly inherited thrombocythaemia.
- GenCC 22 GenCC submitters rate it definitive or strong
▶Actionability
Follow-up with a haematologist, including monitoring of blood counts, since blood cancers have occurred in some affected families. Evidence is limited, and for children there are no agreed guidelines. Because it is inherited in an autosomal dominant way, each child of an affected parent has a 1 in 2 chance of inheriting the change, and testing relatives can show who else carries it.
Read JAK2, and the rest of your genome, with one test.
From $449Free shipping · Results in 6–8 weeks
Get my Genome TestHow JAK2 is laid out
- Coding sequence
- Untranslated region
- Intron
- Direction of transcription
- Known disease-causing sites
- Stretches short reads find hard
Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.
Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).
Nearby genes from Ensembl release 116, on GRCh38.
Exons make up 7 kb of the gene's 144.7 kb; 3,399 of those bases code for the protein.
Sequencing JAK2
3Easy
How hard JAK2 is to sequence with short reads, out of 100
0 · Easy100 · Hard
Almost all of JAK2's exons sit where short reads map cleanly.
What adds to it: the share of JAK2's exons in each kind of hard region
- MappabilityStretches where 100 or 250 bp reads cannot be placed uniquely, so a call there may be missing or wrong. On its own, a gene wholly in this kind of region would score 100.0%
- HomologySegmental duplications: copies elsewhere in the genome, such as paralogues and pseudogenes, at 90% identity or more. On its own, a gene wholly in this kind of region would score 60.0%
- Shared with chrYThe pseudoautosomal regions and the X-transposed region, where chrX and chrY carry the same or nearly the same sequence, so a read from one may be placed on the other. On its own, a gene wholly in this kind of region would score 60.0%
- Reference coverageGaps in the reference assembly nearby, where there is no sequence for reads to align to. On its own, a gene wholly in this kind of region would score 50.0%
- RepeatsTandem repeats and runs of one base, which reads slip on and may not span. On its own, a gene wholly in this kind of region would score 30.2.7%
- GC contentWindows under 25% or over 65% G and C, which library preparation covers thinly. On its own, a gene wholly in this kind of region would score 20.11%
A Dante Labs score from our own research, built on NIST's Genome in a Bottle maps of hard-to-sequence regions.How it's scoredEach bar is the share of JAK2's exon bases in that kind of difficult region. Any one kind can make a gene hard on its own, and each further kind adds less: 0 when no base is in any, 100 when every base is where reads cannot be placed uniquely.
5
positions in JAK2 where ClinVar classes a change as pathogenic or likely pathogenic
None of them falls in a region short reads find hard.
A whole genome covers all 144.7 kb of JAK2, introns included, not only the 7 kb of exons.
ClinVar pathogenic variants (5)
The JAK2 variants ClinVar classifies pathogenic or likely pathogenic for any condition, reviewed by at least one submitter with criteria, and the most reviewed of them. It is ClinVar's public record of the gene, never a result.
- Pathogenic 1
- Likely pathogenic 4
| Variant | Conditions | ClinVar classification | Review status |
|---|---|---|---|
| NM_004972.4(JAK2):c.1849G>T (p.Val617Phe) | Budd-Chiari syndrome and 5 others | Pathogenic | ★★★★2 stars out of 4 criteria provided, multiple submitters, no conflicts |
| NM_004972.4(JAK2):c.1691G>A (p.Arg564Gln) | Budd-Chiari syndrome and 5 others | Likely pathogenic | ★★★★1 star out of 4 criteria provided, single submitter |
| NM_004972.4(JAK2):c.2600G>A (p.Arg867Gln) | Budd-Chiari syndrome and 5 others | Likely pathogenic | ★★★★1 star out of 4 criteria provided, single submitter |
| NM_004972.4(JAK2):c.2813G>A (p.Arg938Gln) | thrombocythemia 3 | Likely pathogenic | ★★★★1 star out of 4 criteria provided, single submitter |
| NM_004972.4(JAK2):c.3284C>T (p.Pro1095Leu) | acquired polycythemia vera | Likely pathogenic | ★★★★1 star out of 4 criteria provided, single submitter |
Traits linked to JAK2
The Human Phenotype Ontology lists these as features of the rare conditions JAK2 can cause. Each trait's page lists the other genes linked to it.
Abnormality of blood and blood-forming tissues
- Extramedullary hematopoiesis
- Increased circulating hemoglobin concentration
- Increased hematocrit
- Increased number of platelets in blood
- Myelofibrosis
- Abnormal shape of platelets
- Acute blood cancer
- Bleeding gums
Show 36 more traits
- Bleeding tendency
- Blood clot in artery
- Blood clot in vein
- Bloody nose
- Bone marrow disease
- Bruising susceptibility
- Increased megakaryocyte count
- Increased red blood cells
- Megakaryocyte nucleus hyperlobulation
- Myelodysplasia
- Platelet abnormalities
- Prolonged bleeding time
- Abnormal megakaryocyte morphology
- Abnormality of blood and blood-forming tissues
- Blood clot in liver vein
- Low number of red blood cells or hemoglobin
- Low platelet count
- Abnormal blood clot
- Acute myeloid leukemia
- Blood clot in portal vein
- Blood spots
- Bone marrow hypercellularity
- Chronic myelogenous leukemia
- Ecchymosis
- Elevated white blood count
- Gastrointestinal bleeding
- Low blood cell count
- Petechiae
- Poikilocytosis
- Blood tumor
- Bleeding in brain
- Increased micromegakaryocyte count
- Increased red blood cell mass
- Myeloproliferative disorder
- Peripheral blood clot
- Thromboembolism
External links
Gene records
Transcript
Protein
Where this comes from
- HGNC: the gene's symbol, name, other symbols and location.
- MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
- GenCC and ClinGen, released 2026-10-23: which conditions the gene is linked to, and how strongly.
- The ACMG secondary findings list, SF v3.2.
- ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
- The Genome in a Bottle genome stratifications, from NIST: the sequencing difficulty score.
- The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
- AlphaFold DB model AF-O60674-F1, version 6, from Google DeepMind and EMBL-EBI (CC BY 4.0): the protein's structure as AlphaFold predicts it, not as measured, and its confidence in each part.
- Data release 2026.10.23-dc0c0517.
Cite this page
Dante Labs. (n.d.). JAK2 gene: Janus kinase 2. Retrieved 24 October 2026, from https://dantelabs.com/genes/jak2
Dante Labs. JAK2 gene: Janus kinase 2 [Internet]. [cited 24 October 2026]. Available from: https://dantelabs.com/genes/jak2
AtlasOne test. A lifetime of answers.
From $449Free shipping · Results in 6–8 weeks