PDK1 and rheumatoid arthritis: A set of eleven upregulated genes, including COX7C, COX7B, PDK1, PDK3, NDUFB8, COX11, NDUFAF4, SUCLG1, NDUFS1, PDHX, and SUCLA2, was identified in RA patients compared to HCs, and characterized as key hub genes with strong correlations to TCA cycle metabolism in RA.