GFRAL and myalgic encephalomeyelitis/chronic fatigue syndrome: Furthermore, recent data show that severe myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a debilitating condition characterized by skeletal muscle fatigue and mitochondrial dysfunction (Morris & Maes, 2014), is associated with increased levels of GDF15 (Melvin et al, 2019), although the role of the GDF15-GFRAL axis in ME/CFS remains to be elucidated.