system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 53-year-old woman comes to the emergency department because of blurry vision, headache, and multiple episodes of nosebleeds over the last few weeks. During this time, she has also been itching a lot, especially after getting ready for work in the mornings. She has had an 8-kg (17.6-lb) weight loss and increasing fatigue during the past 6 months. Her temperature is 37.8°C (100.0°F), pulse is 80/min, respirations are 15/min, and blood pressure is 158/90 mm Hg. Physical examination shows no lesions or evidence of trauma in the nasal cavity. Her face, palms, nail beds, oral mucosa, and conjunctiva appear red. Abdominal examination shows splenomegaly. Her hemoglobin concentration is 19 g/dL, hematocrit is 58%, platelets are 450,000/μL, and erythropoietin level is below normal. A peripheral blood smear shows RBC precursor cells. Which of the following is the most likely underlying cause of this patient's condition?
assistant
Mutated JAK2 gene