The recent debate regarding the possible involvement of xenotropic murine leukemia virus-related virus (XMRV) in chronic fatigue syndrome (CFS) in humans has been intense due to the conflicting results from different studies and the unclear origin of the XMRV virus. In this study, we have addressed this issue by screening 47 pairs of monozygotic twins discordant for CFS using a sensitive PCR assay. The results are clearly negative for all samples. This is consistent with studies showing no evidence for the involvement of XMRV in CFS and supports the possibility that previous positive studies could be caused by laboratory artifacts.
Key words: Chronic fatigue syndrome (CFS), idiopathic chronic fatigue, infectious disease, xenotropic murine leukemia virus-related virus (XMRV), monozygotic twins