The increase in RDW can be attributed to activated inflammatory response in HF on the one hand, and increased inflammatory factors, including IL-1β, TNF-α, and IL-6 that suppress erythropoiesis thereby elevating RDW on the other, as well as insufficient EPO production in HF that causes anemia, also contributing to elevated RDW. The gene discussed is IL6; the disease is anemia (phenotype).