Xenotropic Murine leukemia virus-Related Virus (XMRV) is a gammaretrovirus that was first described in 2006. It has been isolated from human biological samples.
Several reports have associated the virus with familial and sporadic prostate cancer but other reports do not find a link.
Similarly, a possible association with chronic fatigue syndrome has been reported but other studies find no evidence of an association.
XMRV has not been established as a cause of either prostate cancer or chronic fatigue syndrome.
XMRV may be transmitted sexually.
Because XMRV may be a blood-borne pathogen, Canadian Blood Services and Australian Red Cross Blood Service indefinitely defer individuals with a history of chronic fatigue syndrome from donating blood.