SLC40A1 and Parkinson disease: Therefore, it is conceivable that the iron metabolism-related proteins TFR/TF and FPn modulate iron transport between different types of cells in PD-affected brain regions in response to α-syn PFFs treatment, which could impair the normal transport of iron by iron-related proteins in the nigra-striatal system, and the iron deposition in microglia may indirectly cause dysfunction in dopaminergic neurons in PD71,72.