CHST1 and Parkinson disease: Pathway analysis on up- or downregulated genes (PD vs Control) within this population suggests perturbations in sugar/glucose metabolism, due to the downregulation of O-GlcNAcase (OGA) and carbohydrate sulfotransferase 1 (CHST1), which is reported to be an early event in sporadic PD [10] (Fig. 2G, H; Supplementary Table 8).