Most proximal tubule (PT) transcripts of the enzymes catalyzing the steps of the TCA cycle, including citrate synthetase (CS), aconitase (ACO1, ACO2), isocitrate dehydrogenase (IDH1, IDH3A), oxoglutarate dehydrogenase (OGDH, ODGHL), succinate-CoA ligase (SUCGL1, SUCGL2), succinate dehydrogenase complex, subunit A (SDHA), and fumarate hydratase (FH), were lower in T1D versus HCs (Table 4, Figure 3, and Supplemental Figure 4). The gene discussed is IDH1; the disease is type 1 diabetes mellitus.