HQ Team
August 7, 2025: About 67 million people globally living with chronic fatigue syndrome have different genes compared to their healthy counterparts, initial findings from the world’s largest research study on the illness reveal.
The debilitating condition, also called myalgic encephalomyelitis, is a serious, chronic neuromuscular disease characterised by muscle fatigue and neurological disturbances, often triggered by a viral infection.
The disorder causes profound, prolonged muscle weakness after minimal exertion and affects cognitive, autonomic, and sensory functions. Symptoms fluctuate and tend to relapse, with patients often experiencing chronic pain after physical or mental exertion, known as post-exertional malaise.
The disease may also involve cardiac and other systemic symptoms.
Some scientists prefer to combine myalgic encephalomyelitis with chronic fatigue syndrome (CFS) and use the term ME/CFS. This combination results in a disabling chronic illness marked by severe fatigue that does not improve with rest, sleep problems, cognitive impairments such as difficulty thinking and memory issues, dizziness, brain fog, and pain.
No specific tests
It was thought to occur from psychological reasons or laziness. Diagnosis is symptom-based due to the lack of specific tests.
Researchers at the University of Edinburgh uncovered eight areas of genetic code in people with ME/CFS that are markedly different from the DNA of the people without the condition, according to a statement from the university.
This is the first time a study has revealed that a person’s genes are the causative factor of the disease, and suggests that both the immune system and nervous system are involved in its development.
Researchers analysed 15,579 DNA samples with European ancestry from 27,000 people with ME/CFS participating in the project called DecodeME – the world’s largest set of people with the disease.
The eight genetic differences, also known as genetic signals, involve genes linked to the immune and nervous systems.
‘Wake-up call’
At least two of the genetic signals relate to how the body responds to infection, which aligns with patient reports that the onset of symptoms often follows an infectious illness. Another has previously been identified in those experiencing chronic pain, a symptom commonly described by those living with ME/CFS.
As a person’s DNA does not change over time, the genetic signals identified would not have developed because of ME/CFS and are therefore likely to reflect the causes of the disease.
The findings are not yet ready to inform treatment or diagnosis, but they offer vital clues to the disease’s origins and could guide future drug development, researchers said.
“This is a wake-up call,” said Professor Chris Ponting, DecodeME investigator from the University of Edinburgh. “These extraordinary DNA results speak the language of ME/CFS, often recounting people’s ME/CFS symptoms.
“DecodeME’s eight genetic signals reveal much about why infection triggers ME/CFS, and why pain is a common symptom. ME/CFS is a serious illness, and we now know that someone’s genetics can tip the balance on whether they are diagnosed with it.”
‘Ground-breaking’
DecodeME was launched in 2022 to explore whether genes play a role in who develops ME/CFS. Apart from genetic analysis, the study includes questionnaire data, helping researchers better understand the lived experiences of those with the disease.
The study has previously reported that women with ME/CFS have more symptoms and co-occurring conditions than men.
“These results are ground-breaking,” said Sonya Chowdhury, CEO of Action for ME and DecodeME co-investigator.
“With DecodeME, we have gone from knowing next to nothing about the causes of ME/CFS to giving researchers clear targets. This brings ME/CFS in line with other long-term diseases that have genetic components.
