Which are the causes of Polycythemia Vera?

TL;DR: Polycythemia Vera is a chronic blood cancer primarily caused by acquired (somatic) genetic mutations that lead the bone marrow to overproduce red blood cells. The most significant driver is the JAK2 gene mutation, which acts like a "stuck throttle" in the body's blood-cell production system.

What is the underlying cause of Polycythemia Vera?

Polycythemia Vera is classified as a myeloproliferative neoplasm. It is not caused by anything a patient did or did not do; rather, it is the result of a genetic "typo" that occurs in a single hematopoietic stem cell during a person's lifetime. This mutation causes the bone marrow to ignore the body's normal regulatory signals, leading to the uncontrolled production of red blood cells, and sometimes white blood cells and platelets, which thickens the blood.

Is Polycythemia Vera hereditary?

In the vast majority of cases, Polycythemia Vera is not hereditary. It is caused by acquired somatic mutations, meaning they occur in the blood-forming cells after birth and are not passed down from parents to children. While rare familial clusters of Polycythemia Vera have been documented, these are the exception, not the rule.

What role does the JAK2 mutation play?

The primary driver of Polycythemia Vera is a specific mutation in the JAK2 gene. You can think of the JAK2 protein as a light switch that tells the body when to make blood cells. In patients with Polycythemia Vera:

• Over 95% of patients carry a mutation in the JAK2 (V617F) gene.


• This mutation locks the "switch" in the "on" position, forcing the bone marrow to produce cells continuously.


• A smaller percentage of patients may have mutations in the CALR or MPL genes, though these are more common in other related conditions.

Are there environmental risk factors for Polycythemia Vera?

Unlike some cancers linked to external triggers like smoking or chemical exposure, the exact environmental causes of Polycythemia Vera remain unknown. Research is ongoing to determine if there are subtle environmental or lifestyle triggers, but currently, no specific preventive measures have been identified. It is important for our 118 DiseaseMaps community members to know that this is a biological event, not a failure of personal health choices.

Next steps

• Consult a hematologist specializing in myeloproliferative neoplasms (MPNs).


• Ask your physician about molecular testing to confirm your specific mutation profile.


• Join the DiseaseMaps community to connect with others sharing their experiences with Polycythemia Vera.


• Stay informed on clinical trials via the MPN Research Foundation.

Medical disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment.

References

• National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD): Polycythemia Vera.


• Orphanet: Polycythemia Vera (ORPHA:732).


• OMIM (Online Mendelian Inheritance in Man): Polycythemia Vera; PV.


• MPN Research Foundation: Understanding the Science of Polycythemia Vera.