The NIMO-CKD-UK study showed that the mean Hb levels in the >1000 mg IV iron group following Course 1 did not increase beyond 120 g/L, even in patients receiving ESA at baseline, offering reassurance that higher initial doses of IV iron do not elevate Hb to levels that are associated with safety risks (an Hb level > 120 g/L is acceptable for patients not receiving ESA [35]). The gene discussed is GSTM1; the disease is chronic kidney disease.