Scientists say they have developed the world's first blood test to diagnose myalgic encephalomyelitis, also known as chronic fatigue syndrome (ME/CFS).
There are currently no tests for the disease and patients are typically diagnosed based on symptoms, meaning many may remain undiagnosed for many years.
However, some experts not related to study urged caution and said the test needs to be fully validated in more carefully designed and independent studies before it can be considered for use in clinical practice.
Leading researcher, professor Dmitry Pshezhetsky, University of East Anglia (UEA) of Norwich Medical School, said: “ME/CFS is a serious and often disabling condition characterized by extreme fatigue that is not relieved by rest. We know that some patients report being ignored or even being told that their illness is 'all in their head.' Without accurate tests, many patients remain undiagnosed or misdiagnosed for many years.
“We wanted to see if we could develop a blood test to diagnose this disease – and we did. Our discovery opens up the potential for a simple and accurate blood test that can help confirm the diagnosis, which could lead to earlier support and more effective treatment.”
Scientists from UEA and Oxford Biodynamics (OBD) have looked at how DNA folds in patients diagnosed with the disease, which may indicate characteristic features of ME/CFS.
They examined blood samples from 47 patients with severe ME/CFS and 61 healthy adults. The team discovered a unique pattern that consistently appears in people with ME/CFS and is not observed in healthy people, which allowed them to develop the test.
In a paper in the Journal of Translational Medicine, they said the test's sensitivity (or the likelihood of a test being positive if the patient has the disease) is 92%. Its specificity – the likelihood that the test will exclude negative cases – was 98%.
Przezecki added: “This is a significant step forward: for the first time, we have a simple blood test that can reliably identify ME/CFS, potentially changing the way this complex disease is diagnosed and treated.”
Alexander Akulichev, chief scientist at OBD, who funded and co-authored the study, said: “Chronic fatigue syndrome is not a genetic disease that you are born with, so using EpiSwitch 'epigenetic' markers, which can change throughout a person's life, as opposed to a fixed genetic code, was key to achieving such a high level of accuracy.”
However, other experts called for more research to confirm the results and to evaluate the test in a wider group of patients.
Dr Charles Shepherd, medical adviser to the ME Association, said: “These results, obtained using epigenetic profiling, appear to be an important step forward in the search for a diagnostic blood test.
“However, as the researchers note, a diagnostic blood test must be both highly sensitive and specific for this condition. So in this case, we need to know whether the abnormality is consistently present in the earliest stages of ME/CFS, as well as in people with long-term disease who have mild or moderate ME/CFS.”
“We also need to know that, in addition to the fact that the abnormality is absent in healthy people, it is also absent in a number of other chronic inflammatory and autoimmune diseases that cause symptoms similar to ME/CFS and are part of the differential diagnosis of ME/CFS.”
Professor Chris Ponting, head of medical bioinformatics at the University of Edinburgh, said some of the research team's claims were “premature”.
He said: “This test needs to be fully validated in more carefully designed and independent studies before it can be considered for clinical use. Even if it is approved, the test will be expensive, probably (around) £1,000.”
