All are true about the Etiology of primary myelofibrosis , EXCEPT:

Primary myelofibrosis ,Etiological features. The etiology is unknown. JAK2 V617F is present in approximately 50% of patients Mutations in the thrombopoietin receptor Mpl occur in about 5%. Fibrosis is associated with overproduction of transforming growth factor and tissue inhibitors of metalloproteinases Osteosclerosis is associated with overproduction of osteoprotegerin. Ref: Harrison, E-18,P-906.