In addition, deregulation in 2-5A pathway has been documented in immune cells of chronic fatigue syndrome (CFS) patients characterized by abnormally upregulated OAS and RNase L activities and by the presence of a low molecular weight (LMW) 2-5A-binding protein of 37 kDa related to RNase L produced by proteolytic degradation of the wild type protein. This evidence concerns the gene RNASEL and myalgic encephalomeyelitis/chronic fatigue syndrome.