In the study by Qunibi et al. [11], IV ferric carboxymaltose was found to induce a significantly higher increase in Hb when compared with oral iron over an 8-week treatment period in NDD-CKD patients, and in a study by Spinowitz et al. [10], IV ferumoxytol led to a significantly higher increase in Hb from baseline to Day 35 when compared with oral iron in CKD patients. The gene discussed is GSTM1; the disease is chronic kidney disease.