These results suggest the following: (1) in patients with heart failure complicated by anemia, shortness of breath may have been due in part to anemia, and improvement in anemia led to relief of symptoms; (2) improvement in anemia may have contributed to symptom relief in heart failure, which could have subsequently led to improvements in ANP, BNP, or NT-proBNP levels. The gene discussed is NPPB; the disease is anemia (phenotype).