A young woman presents to the clinic for evaluation of a facial rash, as well as symptoms of arthralgias and fatigue. The symptoms started a few months ago and are not resolving. On physical examination, the rash on her face is erythematous and raised, the heart and lungs are normal, and the wrists are swollen and tender on palpation. Laboratory evaluation is only significant for mild thrombocytopenia (90,000/mL). Which of the following is the most appropriate initial autoantibody test?