TGFB1 and myalgic encephalomeyelitis/chronic fatigue syndrome: A recent review including meta-analysis of 38 articles studying all together 77 different cytokines, including interleukins, chemokines and growth factors, found evidence of elevated blood levels only of transforming growth factor beta (TGF-β) in CFS (63% of the studies), whereas other cytokines were not found to be consistently altered in any direction [18].