One of the last great challenges for major, poorly understood chronic diseases that affect millions, is what is fundamental biochemical cause for healthy people who get ill, to sometime not recover, but trigger often lifelong disease call ME/CFS. Most never recover. Most are not diagnosed. Can affect anyone. Excellent review in 2015, see, Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness : Health and Medicine Division
For example of recent Metabomic study of >600 analytes: Naviaux et al: Metabolic features of chronic fatigue syndrome
Can you help millions?