Hi all, with all the interest in VAF and INF I thought I'd post my story after a year on Pegasys. Wishing everyone all the best!
I had a pretty major cerebral venous thrombosis event in 2016 at age 46, after which BMB showed Jak2+. Despite how critical my condition was for a time (thankfully I recovered fully) my labs weren't definitive enough for an MPN diagnosis. Slightly high platelets and spleen size, but all other labs were consistently WNL until 2023. Since I didn't meet criteria for MPN, the only medication I was on during that time was Xeralto for the thrombosis.
In 2023 my HCT and HG increased so we did a nextgen BMB which showed some hypercellularity in the marrow and mild reticulin fibrosis (MF-01). It also showed VAF of 67.2%. My hemotologist was not surprised. PV was confirmed and after some initial phlebotomies to lower HCT I started on Pegasys. I was also feeling a bit off - tired and foggy.
My initial Pegasys dosage was 2.5cc (45 mcg) weekly, increased to 5cc (90 mcg) weekly a few months ago when my HCG crept up. Since then all WNL. I've been tolerating Peg ok, my main issue is mild aches and fatigue a couple days after injection.
Recently I asked for a VAF blood test and learned it is at 52%. I'm not making too much of this and hear there is a % gap between VAF when measured via BMB vs bloodwork.
Anyone is welcome to try to interpret this for me. Maybe I could have reason to be encouraged that Peg is having a good effect, controlling my numbers as well as reducing the overall mutation?
One curious statement in my test results someone here might be able to clarify is:
"The precision of JAK2 mutation percentage measurement is such that values 2 times higher or lower than the reported value are considered equivalent."
In gratitude, cheers.
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Fabfam5
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The term "nexgen" usually means they looked for "non driver" mutations. For PV these are other than just Jak2. (ET is different) Some examples are TET2, ASXL1, DNMT3A. These to varying extents can influence the response to treatments. If your report did not find any of these that should be noted in the details. Likely you had none, otherwise it should been prominently noted.
You're right it's best to compare same to same whether blood or marrow. In the future you should expect to get it via blood since that is a lot more convenient.
That very low precision of +/-2X suggest you got a "qualitative" rather than a "quantitative" test. The former looks for the presence of the mutation, the latter checks how much is mutated.
Which test had that note, the marrow or the blood one? If it was the marrow then your blood test may have been quantitative (they already knew which mutations you have). If so the 52% result should be more precise. You could ask them for more details on this.
There were no non driver mutations in my panel, and the precision note was regarding the blood test, not the BMB.
Interesting qualitative vs quantitative. Thank you, I'll look into that more. I think a year from now the conversation about my VAF will be more interesting, and I'll be sure to have some apple to apples data.
If your latest test was the +/- 2X it won't be useful for next year's VAF comparison. Just thinking, 2X less is not a standard description, they likely mean 1/2 of. So the precision likely is +2X, - 0.5X. Which still doesn't work for 52%, it would be 26-104%. It can't exceed 100.
It's a good idea to inquire what that weird precision really means.
I have only positive things to say about peginterferon. Switched to it after trying very unsuccessfully HU and anagrelide. Their side effects were overwhelming. The only things I have to worry about at this time are platelets which are now just below 600 and constant challenge to raise liver enzymes. Milk thistle is a big help. There is always a push for enzymes to rise 2x normal so milk thistle is a routine supplement. I would take your test results as very good news--trending down! Peginterferon is supposed to help prevent/slow progression. While you have questioned the results of two different tests, I'd take the second one for peace of mind and let the next future test add more data. Many times on this site is reference to being on a journey, not a sprint. Look at trends, not necessarily individual results. Best of luck to your continued good progress.
thank you Mishie14. I’m pleased and grateful to have any kind of effective treatment, and a chance of disease modification. VAF will do what it will do, meanwhile we learn what we can and focus on the positive.
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BMB conflicts blood test result on JAK2
