Essential thrombocythemia is a rare disease of the group of myeloproliferative disorders underlying a malignant monoclonal proliferation of hematopoietic stem cells of the thrombocytic cell series.
The result is a permanently increased platelet count, along with a consecutive thrombosis and bleeding tendency. The exact cause of essential thrombocythemia is unknown. The disease is probably triggered by several mutations caused genetic defects.
Often there is a point mutation on chromosome 9, the so-called JAK2 mutation, which is detectable in about 40% of ET patients. The mutation leads to a dysregulation or permanent activation of the Janus kinase, which has an important role in the signal transduction of the cells.
In principle, all age groups may be affected, but most commonly the disease occurs in adults around the age of 60 years. Most patients with ET remain symptomless for years.
Over time, the clinical picture is dominated by a tendency to vascular occlusion and bleeding. Bleeding typically occurs at very high platelet counts (> 2,000,000 / μl) and is due to platelet dysfunction.
In addition to thrombotic and hemorrhagic symptoms, vasomotor disorders (headache, visual disturbances, atypical chest pain, distal paraesthesia) may also occur. In rare cases, ET can develop into acute leukemia or myelodysplastic syndrome.
Those affected usually have a normal life expectancy if the disease is closely monitored and treated as needed.