HBD and Parkinson disease: A recent transcriptomic meta-analysis identified a significant downregulation of genes associated with hemoglobin and iron metabolism including, hemoglobin delta (HBD), alpha hemoglobin stabilizing protein (ASHP) and solute carrier family 11 member 2 (SLC11A2) in blood of PD, thus reinforcing the relevance of these pathways in the disease pathogenesis (Santiago and Potashkin, 2017).