Q. I have a very high platelet count and JAK2 gene mutation. Does this rule out CML?

Answered by
Dr. Goswami Parth Rajendragiri
and medically reviewed by Dr. Preetha J
This is a premium question & answer published on Nov 11, 2020

Hi doctor,

My platelet has always been high in the range of 600 to 700 x 10"9/L. My other blood count is within the normal range as of today. Ten years ago, I had two BCR or ABL test (peripheral blood) to rule out CML; one test came back positive, the other negative. Which test should I believe? The positive result came from multiplex RT-PCR, the negative from QRT to PCR. I had a JAK2 gene mutation difficulty drawn with peripheral blood, and it came back positive; based on this, the doctor diagnosed me with essential thrombocytosis. Does the presence of the JAK2+ gene automatically rule out CML? I do not take any medication at all. Would it be possible for me to stay in the chronic phase of CML for ten years? Assuming the positive BCR-ABL test ten years ago was the correct one. Can BCR-ABL also detect in normal individuals? In the past two weeks, I have been experiencing pins and tingling on the back of the head and pressure sensation on the forehead. I have taken decongestant and Paracetamol, but the only medication that relieved my symptom is Lorazepam 1 mg. How do I know if this mild headache or migraine is related to ET or something else?



Welcome to

I can understand your concern. Do not worry. I will try to answer all of your questions. Following is my answers and opinion to your questions.

  1. RT PCR (Reverse transcriptase-polymerase chain reaction) is a highly accurate test to check BCR ABL mutation to rule out CML (Chronic myeloid leukemia). So your one positive BCR ABL report could be a false positive report. Your other report was negative. If CBC (complete blood count) and peripheral smear normal at that time, than CML less likely.
  2. JAK2 gene mutation positivity is seen in myeloproliferative neoplasm, especially polycythemia vera and essential thrombocythemia myeloid blood cancer usually. Your platelet count are elevated. Hence elevated platelets along with positive JAK2 gene mutation is suggestive of essential thrombocythemia. It is not positive in CML.
  3. The chance of CML for ten years is less likely. Because in that duration, you might have cancer progression symptoms, especially weight loss, chronic fatigue, enlarged liver, spleen, etc. CML was detected in CBC and PS as well. So your CBC and PS might be normal at that time before ten years, probably as per my assumption.
  4. In a normal individual, BCR ABL mutation is not seen.
  5. Pressure headache seems most likely due to anxiety-like tension headache because it gets relieved by Lorazepam, which is anti-anxiety medicine. However, there is a slight possibility of headaches due to ET (essential thrombocythemia) as well.

In short, according to the provided history, it could be essential thrombocythemia most likely and not CML.

However, in my opinion, you should investigate further with bone marrow biopsy and physical examination, especially liver and spleen palpation, for confirmation of essential thrombocythemia. You can attach all reports and bone marrow biopsy report once done to comment further. I hope I have answered your questions. Let me know if I can assist you also.

Best regards.

Hi doctor,

Thank you for your reply.

I had an ultrasound on the abdomen last month for an unrelated issue; the report said that the liver and spleen size are normal. But this should be enlarged on essential thrombocytosis. For headache, if ET causes it, would Aspirin help? Is there any risk of me taking Aspirin to see if it helps? Last, my CBC, as of recently, is still within normal range except platelet.



Welcome back to

Following is my other answer to your asked question. You are right. In myeloproliferative neoplasm, the liver and spleen get enlarged usually. If the headache is due to PV (polycythemia vera) or ET, then low dose baby Aspirin might help, and there is no risk in taking it. However, you should consult a hematologist for physical examination and bone marrow. Although your CBC report is normal, as JAK 2 (Janus kinase) is positive, it is better to consult a good hematologist for your physical examination and discuss the need for a bone marrow biopsy report for further work up. Bone marrow biopsy will rule out ET (essential thrombocythemia) or PV if present. I hope I have answered your question. Let me know if I can assist you further.

Best regards.

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