Review Question - QID 110009

A 67-year-old woman presents to her primary care provider with fatigue. She reports a 7-month history of progressively worsening tiredness. She also has noticed that she bleeds more easily with minor trauma. Her past medical history is notable for hypertension, diabetes mellitus, and chronic obstructive pulmonary disorder. She takes lisinopril, hydrochlorothiazide, metformin, and glyburide. She has a 45-pack-year smoking history and has a distant history of cocaine abuse. Her temperature is 99°F (37.2°C), blood pressure is 145/85 mmHg, pulse is 92/min, and respirations are 17/min. On exam, there are decreased breath sounds at the bilateral lung bases. Mild splenomegaly is noted. Results of a peripheral smear are shown in Figure A. This patient’s condition is most commonly associated with a mutation in which gene?