At the same time, the levels of iron and transferrin in CSF in fatigue group were prominently higher than those in non-fatigue group (Table 2), and mental fatigue score increased with the elevated levels of iron and transferrin in CSF in PD group, illustrating that compromised iron transportation and subsequent excessive iron deposition in brain might be the potential mechanism of PD with mental fatigue. The gene discussed is TF; the disease is Parkinson disease.