This gene encodes a haptoglobin-related protein that binds hemoglobin as efficiently as haptoglobin. Unlike haptoglobin, plasma concentration of this protein is unaffected in patients with sickle cell anemia and extensive intravascular hemolysis, suggesting a difference in binding between haptoglobin-hemoglobin and haptoglobin-related protein-hemoglobin complexes to CD163, the hemoglobin scavenger receptor. This protein may also be a clinically important predictor of recurrence of breast cancer.