The exact cause of Polycythemia Vera is still unknown. The change in DNA begins Polycythemia Vera (PV). DNA is a molecule present in every living cell, which forms genes the hereditary material of the cell.

DNA is a set of instructions for cells, telling them how and when to grow and divide. The change in the DNA is known as mutation.

PV is a disorder that begins with a single mutation in one cell. All the cells produced by that first mutant cell have the same problem, and they dominate the blood cell production. (This type of DNA abnormality is called a clonal disorder.)

A mutation in the JAK 2 gene causes PV. The JAK 2 gene produces an important protein involved in blood production. More than 90 percent of patients with Polycythemia Vera, and about half of patients with other myeloproliferative disorders, have this mutation.

Doctors and researchers don't understand the full role of this mutation and its implications for treating the disease.

The DNA mutation that causes polycythemia vera occurs after conception meaning that your mother and father don't have it so it's acquired, rather than inherited from a parent. The mutation of the JAK 2 gene cannot be reversed.