IDH3A and myalgic encephalomeyelitis/chronic fatigue syndrome: Some studies suggest that NADH concentrations are significantly lower in CFS patients compared with healthy controls.42, 43, 44 It is likely that high levels of MDHM and isocitrate dehydrogenase observed in CFS may be an adaptive change to deficiencies of NADH which, in turn, has a critical role in mitochondrial ATP production.