An exploratory analysis of the pooled 3-year data for patients who were enrolled in the ruxolitinib arms of the two randomized phase 3 clinical trials COMFORT-I [29] and COMFORT-II [30] showed dose-dependent anemia: mean Hb levels reached a nadir in the first 8–12 weeks and subsequently recovered to a new, lower baseline by week 24 [31, 32]; and RBC transfusions increased during the first 8–12 weeks of treatment [33, 34]. The gene discussed is GSTM1; the disease is anemia.