Tho the JAK2, CALR, and MPL mutations are acquired, not inherited, so multiple family members with acquired mutations that lead to an MPN may well have all been exposed to the same whatever that causes these. I have read recently about how woman have before they are even born all of their eggs, and so exposure of any woman to something might also impact the eggs she is carrying, even before birth. I am the only one in my family with the JAK2 mutation, none of my siblings nor my children having it, tho my first husband died years ago of an idiopathic pulmonary fibrosis, so I have always wondered…It is a puzzle that I hope to live long enough to see solved, where we get these acquired mutations.

That’s very interesting Steve. I have wondered if ET and PV occur in roughly equal numbers and now I kind of know.

My PV followed a pretty straightforward pattern, and I say that with a grain of salt. My mother’s side seems to have thick, iron rich blood and there have been clots. I was tested for Leiden Factor and it came back negative. I do wonder on that family history though

Or it could be that detection rates are also up. There is stroke in my family on my father's side.

I'm the first to be diagnosed with ET, undiagnosed ET is a major cause of stroke.

Did my forbearers simply stroke? Or did they have undiagnosed ET? I'll never know, but it does make ypu think.

Prefibrotic MF. i only read about it for the last years to make that distinction