EFFECT-HF randomly assigned 172 adults with symptomatic heart failure with reduced ejection fraction and iron deficiency (defined as serum ferritin of less than 100 ng/mL or serum ferritin 100 to 300 ng/mL with a transferrin saturation of less than 20%) to receive ferric carboxymaltose, dose-adjusted to target hemoglobin, ferritin, and transferrin saturation levels, or usual care for 24 weeks49. This evidence concerns the gene TF and hydrops fetalis.