Chronic Fatigue Syndrome, also known as postviral fatigue syndrome, is related to irritable bowel syndrome and fibromyalgia, and has symptoms including back pain, fatigue and fever. An important gene associated with Chronic Fatigue Syndrome is RNASEL (Ribonuclease L), and among its related pathways/superpathways are Signal Transduction and Cytokine Signaling in Immune system. The drugs Tetracycline and Doxycycline have been mentioned in the context of this disorder. Affiliated tissues include brain and skeletal muscle, and related phenotypes are Reduced mammosphere formation and homeostasis/metabolism