Published on December 16, 2018
A Patient Power community member wants to know, “Is it common for mutations to change and what does it mean?” Tune in to hear MPN expert Dr. Joseph Scandura from Weill Cornell Medicine provide an explanation as to why tests may result in JAK2V617F and later CALR. Dr. Scandura shares his insight related to varying laboratory tests and sensitivities may play a role in the change.
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Transcript | Can Mutations Change Over Time in MPN Patients?
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So, Jocelyn said, “In 2006 I tested positive for JAK2 V617F. In 2018 I was told that I’m not JAK2 V617F positive, but that I’m CALR-positive. So, is it common for mutations to change and what does it mean?”
So, it’s not common for the mutations to change in terms of going away if they’re present, although there are certainly examples of this happening. It’s not common. What is probably a little bit more common is sometimes people have one mutation or a couple mutations and then sometimes more mutations are found later. And that often, not always, is linked to the disease changing its character itself. So, somebody with polycythemia vera having more of a fibrotic phase of the disease. In this situation,it’s a little hard to know exactly what happened, but there is a fair amount of variability from one laboratory or one test type to another in terms of sensitivity and the specificity of what is being detected.
So, JAK2 may have been at a very, very low level, could have been an erroneous measure, or it could have been at a relatively low level and the calreticulin mutation wasn’t tested for. And then later somebody retested with a different test that wasn’t sensitive enough to pick up the JAK2 mutation and they looked for a CALR and now that’s coming up positive.
So, the testing modality, the type of test that’s being done, and its individual sensitivity is an important part of this story. And it’s a little hard, I think even for many physicians, to sort of get their heads around because it’s not like a blood count where you have international standards and basically a half-dozenequipment makers everybody uses across the world. There are a lot of different technologies, each of which havelittle wrinkles to them that can limit somewhat exactly what’s being reported.