JAK2 and myeloproliferative disorder: Interestingly, PLT count did not correlate with the frequency of act-PLT-CD8 T cell aggregates in patients with CALR mutation (R2 = 0.07; p = 0.209) but had a strong association in JAK2-mutated MPN (R2 = 0.37; p = 0.013) (Figure 2B).