My daughter is currently doing aspirin + monitor. She is largely asymptomatic with the ET, but has other co-occurring conditions that need immediate attention. When she is ready to initiate cytoreduction, one of the interferons would be a first choice.

This is a somewhat complicated question as the genetics involved in Familial MPNs are complex. Familial MPNs need to be distinguished from conditions like Hereditary Erythrocytosis, which are caused by different mutations that can be directly inherited.

The JAK2 mutation cannot be directly inherited. It is not a germline mutation. It is a somatic mutation that is often acquired early in life. There is some evidence that the predisposition to acquiring the JAK2 mutation may be inherited. One of the theories relates to the JAK2 46/1 (GGCC) MPN-Predisposing Haplotype. This haplotype that is thought to increase risk of developing the JAK2 mutation can be inherited. There is a genetic test for this but it is used in research only. There are some panels, like 23&Me that include this gene variation, but these are not clinical test panels.

My daughter and I are both JAK2 positive. I started presenting as ET then progressed to PV. She presents with ET and may be moving towards PV. We are both positive for the JAK2 46/1 (GGCC) haplotype as well.

Here are a couple of articles on the JAK2 haplotype. There is more in the literature if you are interested.

https://onlinelibrary.wiley.com/doi/10.1002/ajh...
https://pmc.ncbi.nlm.nih.gov/articles/PMC3046267/

The role of the JAK2 GGCC haplotype and the TET2 gene in familial myeloproliferative neoplasms

https://pmc.ncbi.nlm.nih.gov/articles/PMC3046267/

Steve - You are amazing. Appreciate this thoughtful answer. All the best to you and your daughter.

I wonder if there are any siblings both with MPN's? Not something I have ever heard of, though I have seen mention of parent/child similarities, a few on this forum I believe.