TF and Parkinson disease: In PD-RLS group, we analyzed the relationship between the levels of iron and related proteins and neurotransmitters and observed that ferritin level was positively correlated with DA level in CSF (r = 0.225, P  < 0.05) and transferrin level was negatively correlated with the levels of DA and 5-HT in CSF (r = −0.395, P  < 0.05; r = −0.230, P  < 0.05; respectively).