HTR1B and myeloproliferative neoplasm: At post‐hoc Dunn's multiple comparisons test thrombotic MPN patients exhibited significantly higher HTR1B relative expression levels compared to non‐thrombotic MPNs (median log10 fold change 3.055 vs. −0.3649, p < 0.0001), as well as to control group (median log10 fold change 3.055 vs. 0.08451, p = 0.0041) (Figure 2A).