MAPKAPK5 and myeloproliferative disorder: This predictive signature consists of five differentially expressed genes in fibrotic MPN: DDIT3, ALOX15, TCF4, MAPK14, and MAPKAPK5. Using this model, we accurately predicted bone marrow fibrosis in the test cohort with a sensitivity of 78% and a specificity of 91%, with an overall accuracy of 88% (kappa = 0.69).