FECH and Parkinson disease: Our study observed that there was a significant decrease in the l-ANK1 group’s blood MPP1, SLC4A1, EPB42, SELENBP1, GYPB, AHSP, HBD, SNCA and FECH genes compared with the h-ANK1 group, which was consistent with the previous study that examined the differential blood gene expression between PD patients and healthy controls [24].