Primary myelofibrosis is a type of blood cancer that affects the bone marrow, leading to the production of abnormal blood cells. This condition causes the bone marrow to become scarred, which disrupts normal blood cell production and can result in anemia, fatigue, and an enlarged spleen. Patients with primary myelofibrosis may experience symptoms such as night sweats, weight loss, and bone pain. The exact cause is often unknown, but genetic mutations, particularly in the JAK2 gene, are commonly associated with the disease. Treatment options may include medications, blood transfusions, or stem cell transplants.