Likewise, the promoter hypermethylation of transcriptional peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α), an important factor in mitochondrial biogenesis and energy metabolism, was negatively correlated with PGC-1α mRNA and mtDNA content in type 2 diabetic patients [42]. The gene discussed is PPARGC1A; the disease is type 2 diabetes mellitus.