FXN and Parkinson disease: Among the many genes evaluated, which include FTL, FTH1, TF, TFRC, IREB2, LTF, CP, FXN, HFE[52], HPX, HAMP, HFE2[53], and FTMT[54], only the G258S polymorphism in the TF gene showed a statistically significant association with PD [17], although the finding was not replicated in a subsequent study [55], and a haplotype in the SLC11A2 gene was found to occur more frequently in PD [56].