Blood methemoglobin levels rose to 3.7% in April 2016 while on 100 mg of dapsone (normal range < 1.5%), but the patient denied any symptoms of increased fatigue, headaches, shortness of breath, or cyanotic extremities, which would have been suggestive of symptomatic methemoglobinemia. Here, HBG2 is linked to methemoglobinemia.