Defects in PGC-1α activity were recently reported in fibroblasts from individuals with early-onset, parkin-deficient PD (Pacelli et al., 2011), and genome-wide association studies identified reduced expression of many PGC-1α-regulated genes in tissues from individuals with PD (Zheng et al., 2010). This evidence concerns the gene PPARGC1A and Parkinson disease.