HAMP and Miyoshi myopathy: Although hepcidin (a hepatic iron-regulatory peptide) typically restricts systemic iron release (Nemeth and Ganz, 2023), MM patients exhibit paradoxical hepcidin downregulation or functional impairment during iron overload, creating a self-reinforcing cycle of iron accumulation that exacerbates disease progression (Maes et al., 2010; Banaszkiewicz et al., 2022).