We found that people with mild to moderate ME/CFS symptoms had more evidence of early-senescence in their memory T cell subsets and MAITs, based on the loss of CD28 expression but absence of CD57 expression, within central memory CD4+ T cells, effector memory and TEMRA CD8+ T cells and lower frequencies of the CD28+ subset in MAITs. The gene discussed is CD8A; the disease is myalgic encephalomeyelitis/chronic fatigue syndrome.