These dysfunctions may arise from impaired pyruvate dehydrogenase (PDH) function identified in muscle cells (390) and serum (184), as well as reduced plasma coenzyme Q10 (CoQ10) levels in ME/CFS blood and plasma (372, 391) that is inversely associated with fatigue severity (391). Here, PDP1 is linked to myalgic encephalomeyelitis/chronic fatigue syndrome.