SIRT1 and Parkinson disease: Notably, although PPARGC1A, gene implicated in the Zheng et al. study [3], was not among the differentially expressed genes in our microarray, this gene was determined to protect dopaminergic neurons when deacetylated by the Sirt1 (sirtuin 1) protein in the MPTP mouse model of PD [12]; SIRT1 expression was increased in PD samples compared to controls at an FDR-level of significance in our microarray.