TET1 and Parkinson disease: Downregulated genes in old Tet1–/– oocytes were enriched in insulin signaling pathway, Parkinson’s disease, pathways in cancer and sphingolipid signaling pathway, and genes upregulated in old Tet1–/– oocytes enriched in spliceosome, choline metabolism in cancer, and phospholipase D signaling pathway (Figure 3B).