GCSH and chronic apical periodontitis: Among these, four CRGs were found to be down-regulated in chronic apical periodontitis (CAP), namely Nuclear Factor Erythroid 2-Related Factor 2 (NFE2L2), Dihydrolipoamide S-Succinyltransferase (DLST), Solute Carrier Family 25 Member (SLC25A3), and Glycine Cleavage H Protein (GCSH).