POLG and brain disorder: Among the 44 CpGs in younger mice (~4 months old), the age‐associated genes that underwent the most significant changes due to metabolite effects (p <10–5, FDR <0.05) were related to 1C metabolism, such as Amd‐ps6 (S‐adenosylmethionine decarboxylase) or Dip2b (encoding a protein that contains a binding site for DNA methyltransferase 1 and is near a fragile folate‐sensitive site); early development, such as the Mecom or homeobox genes Hoxb8, Hoxc4 or Hoxc12; and brain disorders, such as Slc25a12 (which is present at high levels in parvalbumin interneurons), Polg or Unc80 genes.