T-cell-related gene sets were most highlighted in RA, including ‘abnormal CD8+ T-cell physiology (P = 9.68 × 10−6)’, ‘abnormal lymphocyte morphology (P = 3.06 × 10−5)’, and ‘increased T-cell number (P = 3.20 × 10−5)’. The gene discussed is CD8A; the disease is rheumatoid arthritis.