SLC7A11 and Parkinson disease: Involvement of the antioxidative protective mechanism system xc− was also documented in a recent study by Vallerga et al. From this blood-based methylome-wide association study of PD involving meta-analysis of 229 K CpG probes in 1132 cases and 999 controls from two independent cohorts, the group identified that the cg06690548 on chromosome 4 is significantly associated with PD and cg06690548 hypermethylation in PD is associated with downregulation of the SLC7A11 gene, which codes for system xc− [178].