PPARGC1A and polycystic ovary syndrome: In another study, changes in the level of TCA and NAD catabolism in the follicular fluid, along with OS in cumulus cells (CCs), demonstrated a downregulated mitochondrial biogenesis rate, mtDNA, MMP, and PGC-1α gene expression and an upregulated PGC-1α promoter methylation rate in women with PCOS, compared to control group CCs [55].