Although CD4 + T cells are recognized as key drivers of RA pathogenesis (Weyand et al. 2000), CD8 + T cells with an inflammatory phenotype and oligoclonal T cell receptor (TCR) repertoire are also present in enriched numbers in synovial tissue (Cho et al. 2012; Carvalheiro et al. 2015; Savola et al. 2017), highlighting their potential role in the development and progression of RA. The gene discussed is CD8A; the disease is rheumatoid arthritis.