Hey, Didn't You Used to be the Cause of CFS?

January 17th, 2010

Hey, Didn’t You Used to be the Cause of CFS?

The report last year that xenotropic murine leukemia virus-related virus (XMRV) was found in a high proportion of patients with Chronic Fatigue Syndrome (CFS) caused quite a stir — which is totally understandable given how frustrated the people with CFS are with the lack of adequate explanations for their suffering.

The investigators of the original report even began referring patients to a commercial lab (question #5) to get tested for the virus.

Now some British researchers weigh in. Their findings:

Patients in our CFS cohort had undergone medical screening to exclude detectable organic illness and met the CDC criteria for CFS. DNA extracted from blood samples of 186 CFS patients were screened for XMRV provirus and for the closely related murine leukaemia virus by nested PCR using specific oligonucleotide primers.
(snip)
XMRV or MLV sequences were not amplified from DNA originating from CFS patients in the UK.

Oh darn.

One possible explanation for the negative finding is the differing epidemiology of XMRV in North America and Europe, something also noted in studies of XMRV and prostate cancer.

But the results certainly reinforce what I have suspected for some time, which is that CFS most likely has multiple causes — some infectious, some allergic, some environmental, some emotional, but all yielding a similar clinical phenotype due to underlying genetics and how an individual responds to illness. Yes, XMRV might cause CFS in some people — but seems highly unlikely it does so in all.

I wish it were simpler than that, but alas don’t think it will be.

(Nice summary of the controversy here in ScienceNOW.)

HIV and ID Observations

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January 17th, 2010