Medicine All are true about the Etiology of primary myelofibrosis , EXCEPT: A JAK2 mutation is seen in 50 % cases B Overproduction of transforming growth factor C Overproduction of osteoprotegerin D Mutations in the thrombopoietin receptor Mpl occur in 50% 💡 Explanation All are true about the Etiology of primary myelofibrosis , EXCEPT: ✓ Correct Answer: D. Mutations in the thrombopoietin receptor Mpl occur in 50%