The assumption that pro-inflammatory cytokines may pathogenetically be relevant for fatigue relies on laboratory findings that (1) pro-inflammatory cytokines (IL-1, IL-6, TNF-alpha, and Il-12) were positively correlated with fatigue in MS (50–52), (2) TNF-alpha was correlated with the severity of fatigue in MS (52), and (3) TNF-alpha in animal experiments was able to trigger a fatigue syndrome (53). The gene discussed is IL6; the disease is myeloid sarcoma.