JAK2 Gene Mutations: Linked Conditions and Clinical Trials
The JAK2 gene sits on chromosome 9p24.1, and its full name is Janus kinase 2. Orphanet links JAK2 to 6 rare conditions and lists variants in the gene as a cause of 4 of them. Trial Friend's Polycythemia Vera, Essential Thrombocythemia and Myelofibrosis pages list JAK2 among the genes behind each condition. As of September 29, 2026, 16 recruiting or soon-opening trials on ClinicalTrials.gov name JAK2 as a gene.
Other symbols for JAK2 in gene databases: JTK10.
What the JAK2 gene does
JAK2 makes a signaling protein in the JAK/STAT pathway that tells cells to grow and divide. It is especially important for how stem cells in the bone marrow make red cells, white cells and platelets.
Summarized from the JAK2 page on MedlinePlus Genetics, U.S. National Library of Medicine, checked September 29, 2026.
Conditions linked to JAK2 on Trial Friend
These condition pages list JAK2 among the genes behind the condition, checked against genetics references when each page was written.
Nearly all patients carry an acquired JAK2 variant in blood cells; it is not inherited.
Acquired driver mutations in blood-forming cells (JAK2 V617F most common, then CALR, then MPL) are tested on peripheral blood; rare familial cases are autosomal dominant.
Driver mutations are acquired in blood-forming cells and are not inherited; JAK2, CALR and MPL testing on blood or marrow is standard for diagnosis.
JAK2 mutation clinical trials
These recruiting or soon-opening trials mention JAK2 as a gene in their title, summary, eligibility rules or keywords. Some want people with a variant in it, and others study it more broadly, which is why each trial's own words are shown. In cancer trials the gene change is usually one found in the tumor rather than one a person inherited.
16 trials, checked September 29, 2026. The list refreshes from ClinicalTrials.gov every few hours.
All conditions linked to JAK2 gene mutations
Orphanet records how each gene relates to each condition. Orphanet links JAK2 to 6 rare conditions and lists variants in the gene as a cause of 4 of them.
- Causes it, acquired. Variants that arise during life in the tumor or affected cells cause the condition. They are not inherited.
- Causes it. Disease-causing variants in this gene are a direct cause of the condition.
- Fusion gene. The gene is part of an abnormal fusion found in the tumor, not usually inherited.
- Being studied. Researchers suspect a role that isn't confirmed yet.
JAK2 genetic test results and what a variant can mean
Labs sort each variant they find into 5 groups, from pathogenic and likely pathogenic through uncertain significance to likely benign and benign. Only the first 2 are usually treated as the cause of a condition. A variant of uncertain significance, or VUS, is one without enough evidence either way yet, and labs can reclassify it as research builds.
A genetic counselor or your doctor can explain what a specific result means for you and your family. Our genetic testing guide covers the terms, and MedlinePlus Genetics from the National Library of Medicine has a plain-language page on JAK2.
JAK2 gene questions
What does the JAK2 gene do?
JAK2 makes a signaling protein in the JAK/STAT pathway that tells cells to grow and divide. It is especially important for how stem cells in the bone marrow make red cells, white cells and platelets. This summary follows MedlinePlus Genetics from the U.S. National Library of Medicine.
Are there clinical trials for people with JAK2 gene variants?
As of September 29, 2026, 16 recruiting or soon-opening trials on ClinicalTrials.gov name JAK2 as a gene. Each one is listed on this page with the words from the trial that mention the gene. ClinicalTrials.gov also lists 61 open trials for Polycythemia Vera, 54 for Essential Thrombocythemia and 114 for Myelofibrosis, and Match Me on Trial Friend can check those against age, sex, location and treatment history.
What conditions are linked to the JAK2 gene?
Orphanet links JAK2 to 6 rare conditions and lists variants in the gene as a cause of 4 of them. They include Essential thrombocythemia, Polycythemia vera, Primary myelofibrosis, Familial thrombocytosis, Breast implant-associated anaplastic large cell lymphoma and Budd-Chiari syndrome. Orphanet is the European rare disease database run by INSERM in Paris.
Is Polycythemia Vera inherited?
Nearly all patients carry an acquired JAK2 variant in blood cells; it is not inherited.
Is Essential Thrombocythemia inherited?
Acquired driver mutations in blood-forming cells (JAK2 V617F most common, then CALR, then MPL) are tested on peripheral blood; rare familial cases are autosomal dominant.
What does a JAK2 variant of uncertain significance mean?
A variant of uncertain significance, or VUS, is a change in the gene that labs don't yet have enough evidence to call disease-causing or harmless. It is not used on its own to diagnose a condition, and labs can reclassify it as research builds. A genetic counselor can explain what a specific result means for you and your family.
Sources
- Gene and condition links from Orphadata (Orphanet, INSERM US14), used under CC BY 4.0, read September 29, 2026.
- Trials from ClinicalTrials.gov, read September 29, 2026.
- JAK2 gene, MedlinePlus Genetics, U.S. National Library of Medicine.
- Inheritance and gene notes from the Trial Friend condition pages above, each checked against genetics references.
Other gene pages
The gene search covers every gene Orphanet links to a rare disease.