In most cases, CKD-related anemia is due to several complex pathogenic mechanisms, like (1) erythropoietin (EPO) deficiency; (2) iron deficiency due to blood loss or increased hepcidin levels; (3) reduced red cell life span; (4) inflammation and comorbidities; (5) reduced marrow response to EPO; (6) B12 and/or folic acid deficiencies. The gene discussed is EPO; the disease is anemia (phenotype).