@jewelfaux and @nypara66, You’re both correct. It is possible to determine if a patient has the JAK2 mutation without the need for a bone marrow biopsy. It’s done through blood work.

ET and PV are myeloproliferative diseases. This means there is a glitch somewhere that’s causing an overproduction of blood cells. The defective JAK2 gene can be one of several potential causes. A definitive diagnosis can determined with a bone marrow biopsy.
The bone marrow is the heart of the blood manufacturing site in the body. The results of that biopsy, a core sample of the marrow, gives the doctor an overall picture of the health of the marrow and its ability to provide healthy blood products.
https://www.healthline.com/health/cancer/myeloproliferative-disorders#causes-and-risk-factors
I know, they’re no one’s favorite tests, but on occasion the biopsies are necessary. I’ve had 13 of them and didn’t mind the last 10. They were done under mild sedation and I woke up to juice and Lorna Doone cookies. 😉

I agree with the dr,if treatment for your case will be exactly the same either way,so no need to get inside the bone marrow at least at the beginning, I think maybe he will ask for it after you complete your treatment to see the results

Thank you.