FAQs

We analysed  DNA samples from people with ME/CFS and compared them to the DNA of people without ME/CFS to look for genetic differences between the two groups. We conducted a type of research called a genome wide association study (GWAS), which is a very large genetic study that aims to uncover biological roots to a disease. Our GWAS looked at over 8 million places across the genome to reveal areas where the genetic code differs between our participants and those without ME/CFS. These differences can point to genes and systems that play a role in someone developing the illness.

You can read more about the science behind the study here.

DecodeME is the world’s largest study of ME/CFS, and it is the scale of the study that has made it possible to detect meaningful genetic differences that hadn’t previously been discovered. Earlier studies involved much smaller numbers, which made it harder to detect clear genetic signals. Thanks to the thousands of people with ME/CFS who participated, we were able to uncover differences that may not have been identifiable had we studied a smaller group.

The results are statistically significant, which means they are based on well-established scientific standards that geneticists use in research.  Our large cohort also makes our results more robust, and we expect to build on these results going forward with further analysis and publications.

A preprint is a scientific paper that has been shared publicly before it has been peer reviewed (a formal review process conducted by other scientists). We wanted to share our initial findings as soon as possible and posting our results as a preprint allows the ME/CFS community, researchers, and clinicians to access our discoveries without delay. We hope this will help accelerate research and provide a greater understanding of the condition.

Our analysis is ongoing, and once complete, we will send all our findings for peer review and publication.

We collected 18,051 DNA samples from people with ME/CFS across the UK. After DNA extraction, genotyping and quality control, we had data for 16,730 samples suitable for GWAS analysis. We then matched the ancestry of the participants samples with those of the control group to ensure consistency, this meant 15,579 DNA samples were used for these initial results. We then compared these samples to a population of 259,909 people without ME/CFS. These large numbers allowed us to find genetic differences across the two populations. Future research could build on our results, through analysis of all DNA data collected.  Researcher access – DecodeME

This is because we had to closely match the ancestry of the study samples with those of the control samples from the UK Biobank, which were largely of European ancestry. This was to be sure that the differences we are identifying are more likely to be because of ME/CFS, and not because of differences in ancestry. An ongoing analysis uses all study samples from all ancestries.  

ME/CFS is a complex condition, so from the beginning of DecodeME, we didn’t expect to find just one gene responsible. Like other conditions such as Parkinson’s or diabetes, ME/CFS is influenced by small differences in several genes rather than in one gene only. In DecodeME, we looked at over 8 million points across the genome and found 8 regions, where people with ME/CFS were more likely to have certain genetic differences. These regions give us important clues about the biological processes that may be involved in the illness.

We found that people with ME/CFS are more likely to carry certain DNA differences in eight regions of their genome, and these variants tell us about possible biological causes of ME/CFS. Most of these regions contain several genes. Our methods did not allow us to conclusively locate the ones most relevant to ME/CFS in each region, but public data allowed us to pick out the most likely ones. Three of the most likely genes produce proteins that respond to an infection. Another likely gene is related to chronic pain. Overall, our initial genetic results show that ME/CFS is partly caused by genes related to the immune and nervous systems. 

You can read a summary of our genetic findings in our blog post.  Or you can read the full preprint paper. 

Our results show that people with ME/CFS have subtle genetic differences in how their bodies detect and respond to infections. This doesn’t mean that infection itself causes ME/CFS, but it may mean the way their immune system reacts to the infection increases the risk of developing the condition. Further studies are needed to explore this potential link in more depth. 

DecodeME did not look for different types of ME/CFS, but this is something our dataset allows future research to explore (link to data access). Our results show there are shared biological features amongst people with ME/CFS, but it’s also possible that different subtypes exist. The Precision Life LOCOME project  is using data collected as part of DecodeME to explore this further.   

The genes we’ve identified don’t directly cause ME/CFS on their own, but their genetic differences do increase the likelihood of someone develops ME/CFS, much like how certain genes are linked to conditions such as diabetes or Parkinson’s. They are an important piece of the puzzle, but not the whole picture. Having one or more of these genetic differences does not fully determine whether someone will get ME/CFS. There are likely many contributing causes of ME/CFS, but these findings help us point towards more specific biological pathways involved in the development of the condition.  

All of the eight genetic differences identified are statistically significant which means they are all important discoveries. Statistical significance helps us decide if the difference or relationship we observe in data is likely to be real, not just due to random chance. We now need research to investigate each genetic signal further to fully understand their role in ME/CFS. They all have the potential for further research to lead to treatments and other important discoveries. 

No, these findings are based on large-scale patterns across the thousands of people with ME/CFS that we studied. They show that, on average, people with ME/CFS are more likely to have these differences than people without ME/CFS. These signals are about what we can see across populations, not individuals. 

Our genetic code is something we are born with, and it stays the same throughout the course of our lives. The differences we’ve found were present from birth in those who have them. However, this doesn’t mean someone was predestined to get ME/CFS, but it is a factor in whether or not the condition is later developed. 

Our findings suggest there are differences in risk for ME/CFS depending on the genes inherited. We know that ME sometimes runs in families, which also suggests that genetics can play a role, but it’s just one piece of a much bigger picture that includes things like infections and other environmental factors. So having these genetic differences doesn’t mean that someone will definitely develop ME/CFS, it just means their risk might be slightly higher.

No. Having these genetic differences does not mean someone with ME/CFS will never recover or improve. These genetic differences may influence someone’s risk of developing ME/CFS, or how their body responds to certain triggers, but they don’t forecast someone’s future. Many other factors also shape how ME/CFS affects a person over time, including biology, environment, support, and treatment.

Our findings have pinpointed eight areas of the genome that are linked to ME/CFS. We don’t know exactly how these genetic differences interact with triggers, and further research is needed to understand this. However, our findings do support the idea that people with certain genes may be more susceptible to ME/CFS when exposed to a trigger such as an infection.

These results have identified 8 specific differences in the genome that are more common in people with ME/CFS. The regions around these 8 specific differences include genes already known to play a role in both the immune system and the nervous system. These results provide important clues about where to focus future research and which areas of science are most relevant.

The eight DecodeME genetic signals aren’t related to depression and anxiety. Because many more signals remain to be found in the future, we cannot say that there will be no connection found between depression or anxiety and ME/CFS. 

Some people with Long Covid experience symptoms that overlap with ME/CFS, such as post-exertional malaise, fatigue and brain fog. While DecodeME didn’t specifically study Long Covid, 729 of our participants reported that they developed ME/CFS following a COVID-19 infection. More studies are needed to explore the links between ME/CFS and Long Covid in detail.

The signals we have found are different from those found in other illnesses to date, except for the one on chromosome 17 that was previously found in people experiencing chronic pain.   

DecodeME was designed to study the genetics of ME/CFS across thousands of people to find patterns at a group level. This means that we can’t say what the results mean for any one individual. We understand it’s natural to want to know how these findings relate to your personal experience, but the study cannot provide individual feedback, diagnoses or treatment advice. DecodeME provides a firm foundation on which biological clues will be uncovered that will shape future research and, in time, lead to better care and answers for everyone affected by ME/CFS.

DecodeME was launched because we knew far too little about the biology of ME/CFS, and we needed to use the tools of genetics to change that. Our findings confirm that ME/CFS is partly genetic and lay the groundwork for future research into how the genetic regions we’ve identified may contribute to its development. This could eventually lead to tests or treatments, but more research is needed.

DecodeME’s purpose was to gain an understanding of the biological roots of ME/CFS and how genetics could contribute to developing the condition. By identifying genes linked to the immune system and the nervous system, the study opens the door for scientists to explore what’s going wrong in ME/CFS at a molecular level. This deeper understanding could, in time, lead to treatments that target the root causes of the illness.

DecodeME has found that genes contribute to someone's chances of developing ME/CFS. Our findings put ME/CFS on an equal footing to other serious illnesses that have a genetic contribution like Parkinson’s and diabetes.  Our blog has more information about the results. You can also find out more on our social media channels. 

You could signpost them to our blog or the full preprint paper. While these results don’t yet change how ME/CFS is diagnosed or treated, they do help build a clearer scientific understanding of the condition. Over time, this could lead to better recognition, support and care for people living with ME/CFS.   

We’ve already published findings from the first DecodeME questionnaire (link), which gave valuable insights into the experiences of people with ME/CFS. Although the main study wraps up in August 2025, we hope to continue analysing the questionnaire data in future. We’ve also made the data available to other researchers through our data access process, so it can continue to support important research beyond DecodeME.

DecodeME’s funding ends in August 2025.  However, Action for ME and the University of Edinburgh are committed to continuing analysis and scientific work, including peer review and publication, beyond this point.

The DecodeME findings are a springboard for future ME/CFS research. Now that we've identified genetic signals linked to ME/CFS, researchers can start investigating exactly what’s happening in the body - for example, by specialist scientists delving deeper into each genetic region found. These discoveries open new avenues for research, potential drug development or repurposing, and targeted treatments. DecodeME’s findings have laid the groundwork for a new era of ME/CFS research, and our rich dataset is available for data access applications and is already driving new discoveries forward.

DecodeME has built the largest ever cohort of people with ME/CFS who have created a rich dataset through their participation in both our genetic study and through our extensive questionnaires. This is already helping researchers better understand the different ways ME/CFS affects people, which could inform how participants are selected or grouped in future studies - for example, by onset type, severity, or biological differences. Having a well-defined cohort improves the quality and impact of future research. The DecodeME questionnaires are available publicly, and we will make our algorithms for cohort selection available to other researchers on request.

With your help and support, DecodeME has built the world’s largest data set on ME/CFS.

The DecodeME data access process will permit approved researchers to access this data set for use in other own research projects.

We are opening the application process to researchers employed by reputable and bona fide institutions, who can demonstrate relevant experience and expertise.

All applications for data will be reviewed thoroughly by our Data Access Committee and will only be approved if both the applicant and the project meet strict eligibility criteria, including on PPI involvement, ethics, data security best practice, and the potential for an outcome that will benefit the ME/CFS community. The committee will make sure that we only share DecodeME data with studies that meet our high standards and are ethical and worthwhile.

Consistent with our rigorous data privacy policy, any data shared will be de-identified and will only be shared if participant consent has been given.

Before sharing any data, approved applicants will sign a legal contract to ensure their correct handling and use of the data.

Your genetic and/or other data could also help researchers in projects, other than DecodeME, make discoveries about both ME/CFS and other diseases.

Having data on thousands of people means these scientists could quickly find answers and clues that would take them years to discover if they had to start recruitment from scratch.

DecodeME are offering data access to other approved researchers in the hope that it will help accelerate research towards possible diagnostic tests and treatments for ME/CFS.

86% of DecodeME participants consented to the following:

“I’m happy for my data to be shared with other researchers in future studies approved by DecodeME. The studies might be about diseases other than ME/CFS. I understand that it won’t be possible to identify me from my data and that my NHS health data won’t be shared.”

We will only share your de-identified data and samples with other approved researchers if you have given us your consent as above.

In addition, 95% of DecodeME participants consented to being contacted for new research projects.

The data accessed by approved researchers will vary from project to project and can include samples or data derived from the DNA samples and questionnaire data. All data will be de-identified. The data shared will vary from study-to-study and we will only share the minimum amount of data which is required to meet the study objectives.

As with DecodeME, only the approved and individually named study team and their supply chain partners will have access to the de-identified data. This might include universities or medical companies, and might be in other countries outside the UK.

DecodeME will only consider giving Data Access to researchers employed by reputable and bona fide institutions, who can demonstrate relevant experience and expertise.

All applications for data will be reviewed thoroughly by our Data Access Committee, which includes Patient and Public Involvement (PPI) representation. The committee will make sure that we only share DecodeME data with studies that meet our high standards and are ethical and worthwhile.

Applications will only be approved if both the applicant and the project meet strict eligibility criteria, including on PPI involvement, ethics, data security best practice, and the potential for an outcome that will benefit the ME/CFS community.

Consistent with our rigorous data privacy policy, any data shared will be de-identified and will only be shared where participant consent has been given.

Only the data required for each research project will be shared. We won’t share personal details that could identify you.

The new researchers must agree to treat your data with respect and to keep it secure.

Before sharing any data, the legal team of approved applicants will sign a contract to ensure their correct handling and use of the data.

All data and samples will either be destroyed or returned to DecodeMe at the end of the agreed (and legally contracted) access period.

You can read the full DecodeME data access policy here.

Please see here for a list of approved projects.

No. The data access process is only open for applications from researchers employed by reputable and bona fide institutions, who can demonstrate relevant experience and expertise.

If the research project requires participants to be recontacted, either to ask if you want to take part in a new study, or to collect extra data, you will be contacted in the first instance by DecodeME to ask if you wish to take part. Only those participants who initially consented to being recontacted in this way will be invited.

We used the 2015 Institute of Medicine (IOM), now known as the National Academy of Medicine (NAM) criteria, or the 2003 Canadian Consensus criteria, but we did not use the Oxford or NICE 2007 criteria. Given that people with ME, ME organisations, and ME/CFS biomedical researchers all regard Post-Exertional Malaise (PEM) as a defining symptom of the disease, this will be a mandatory symptom.

We undertook an online survey and the majority of people supported this. These criteria were also agreed at the MRC/NIHR Workshop with researchers, patients and carers.

Full participant recruitment started in September 2022.

DecodeME only recruited participants in the UK (England, Scotland, Wales, N. Ireland). 

Participants needed to be 16 years old or over to take part.

Researchers working at universities, in government departments, at charities or other organisations (including commercial companies) across the world can apply to access our research data.

Our Data Access Committee will assess each application. We’ll only let researchers have access to our data if they’re from reputable scientific institutions and are doing ethically approved projects. Our committee will decide whether the researcher needs the requested data to conduct the research, and whether they’ll do the project in line with the commitments we’ve made to you. We’ll only share data in a way that protects your confidentiality and we’ll only do it with your consent.

A DecodeME committee of a scientist, a patient and a charity representative will strictly control access to the data.

• We won’t share any personal details that could identify you, or any of your NHS health data.
• The researchers must agree to treat your data with respect and to keep it secure.
• They might work for universities or medical companies, and might be in other countries.

The consent form asked you if you’re happy to share your data.

We take sample and data security, and patients’ privacy, very seriously. All samples and data will be kept secure according to the UK’s and international highest standards, overseen by ethical review. All institutions contributing to this project have adopted these standards and use them routinely, and comply with the Human Tissue Act 2004 and all other relevant regulations and legislation, including the General Data Protection Regulation (GDPR).

The University of Edinburgh has extensive experience in doing research that requires recruitment of a large number of people, and always ensures the highest level of privacy for participants and full compliance with ethical standards and legislation.

For more specific information on how we protect your identity please see our Participant Information Document and Privacy Notice.

Patient and public involvement (PPI) has been central to the development of the study, via our PPI Steering Group. You can find out who the PPI Steering Group members are on the About Us page on this website. We also have PPI members in other delivery teams in the project who provide deep insight and lived experience of ME/CFS.

We have also incorporated feedback and ideas from the wider community into the study design. Some examples:

• PPI SG consulted the ME community on the criteria for inclusion in the study and decided to use the Canadian Consensus or Institute of Medicine and not Fukuda criteria as a result.
• PPI recognised the need for a paper-based questionnaire, as well as an online one, for people wanting to participate.
• PPI helped to rewrite the study questionnaire and had extensive involvement in the DecodeME questionnaire
• DecodeME has used the expertise of people with ME/CFS to develop our marketing strategy and budget.

To find out more about how patient and public involvement has impacted the study, you can read this blog post.

No, we prefered to spend the project’s funds only on participants with ME/CFS, by taking advantage of existing data from the UK Biobank on controls (people who do not have ME/CFS).

A genome-wide association study (GWAS) is a very large genetic study that seeks to uncover some of the biological roots of ME/CFS. By probing small DNA differences between people, a GWAS can help to pinpoint the genetic causes of disease and guide drug development. This design has previously been helpful in identifying genes together with molecular and cellular pathways that contribute to disease risk. (Read more about the science of GWAS.)

To work well, the study needs to recruit around 25,000 people with an ME/CFS diagnosis whose DNA will be compared with that of an even larger number of non-ME/CFS matched controls. These will be people from a similar population who do not have ME/CFS drawn from the half-million-strong UK Biobank.

A GWAS has the major advantage that its results indicate root causes of illness, because DNA doesn’t change with ME onset, so GWAS findings reflect causes rather than effects of illness. With most other approaches, it is not usually possible to know if findings indicate the effects of illness, or the cause. For example, people who are unable to exercise are likely to show molecular changes that are solely due to being sedentary, rather than highlighting the root causes of their disease.

GWAS have been successfully applied to many different diseases (asthma, schizophrenia, diabetes, pulmonary disease, etc.) and traits. We believe that it is time that ME/CFS science took full advantage of this cutting-edge genetics approach which is entirely complementary to approaches taken by other ME/CFS researchers.

Until the first GWAS study for an illness is done, it is just not possible to know how meaningful its findings will be. However, we’ve chosen to study the DNA of 25,000 people with ME/CFS because other projects of this size commonly found around five causal links between DNA and disease diagnosis. ME/CFS could have many independent genetic causes and a study of this size will have a chance of revealing part of this potential spectrum of genetic causes.

We will release preliminary results as soon as we can, prior to publication. The sooner we can recruit participants, the sooner the results will be released. The project will be delivered by August 2025.

No — the lead investigator for the project is human genetics specialist Chris Ponting, Professor for Medical Bioinformatics at the MRC Human Genetics Unit. Professor Ponting and all other researchers in this project are focused on biomedical research.

Our goal is to identify causes of ME/CFS. For this we will first isolate and analyse patients’ DNA from their saliva samples. We will then look at around a million common variants in DNA and see if any of the variants are more or less common in patients than seen in control individuals. Questionnaire data such as age, type of onset and symptoms will be used to gain a better understanding of patients’ background and illness and we will link this survey data to their genetic data.

We also ask patients if they are willing to provide us access to their electronic health record. This would help us to get a more detailed understanding of patients’ illness, progression, and symptoms, but would be entirely optional and will not affect eligibility for the study.

We need a very large number of DNA samples for a GWAS study, typically at least 10,000–20,000, which is far in excess of the size of the UK ME/CFS Biobank.

We cannot know this. However, this will not impact our findings significantly, because the fraction of controls in this situation will likely be <1%, assuming a population prevalence of 0.4%.

There will be no attempt at identifying related individuals, other than as a routine part of the statistical analyses. All data is confidential and analysed anonymously.

This is highly likely. The risk of having a complex disease such as an autoimmune condition is altered by many, many different DNA letters scattered around the human genome, and we think it is likely that it will be the same for ME/CFS. The genetic variants all could have the same effect (for example, muting the body’s immune system) but might have separate effects on different bodily processes.

Gaining a better understanding of how ME/CFS affects people is the first step to developing effective treatment options.

Our initial findings highlight the differences in peoples experience of ME/CFS and this will help to inform the knowledge base on ME/CFS and guide future research.

Additionally, the DNA stage of the study aims to identify biological causes of the illness. For more information on how this can inform research and treatments read our blog post: DecodeME – A Treasure Map. 

If you take part in DecodeME, we won’t give you any information about your own individual genetic findings. This is because there are many practical and ethical issues that make it difficult to give personal DNA results to people who take part in research studies.

When people sign up to this study, they are given the option to consent to being contacted about taking part (directly, or by agreeing to share samples and data from this study) in new studies about ME/CFS. This will make it much easier for researchers to recruit participants for studies, speeding up the pace of research. This will all be explained in the consent section when signing up to the study and is an optional part of participating.

Not everyone who takes part in DecodeME will be asked to provide a DNA sample. This is because we are using narrowly focused criteria, focused on IOM/NAM & CCC.  This does not mean that they do not have ME/CFS - only that they aren't eligible for the DNA stage of this study. This could be for a number of reasons (e.g. how their symptoms present for example).

Unfortunately, due to the large size of the study and the importance of avoiding any bias, we are unable to inform participants of the reason they did not meet this criteria. However, the answers you provide at the questionnaire stage are still valuable to ME/CFS research and participants may still be contacted about future research opportunities if they consented to this.

If you are not asked to provide a DNA sample, you are still a DecodeME participant and the information you have provided in the questionnaire is incredibly useful to ME/CFS research. 

For more information on the study criteria and methods used, you can read our published study protocol on the BMC Neurology website.

No, it will not be possible to change your answers after you submit the questionnaire.

Mind

Mind provide a guide to taking the first steps to seeking mental health support. They can help you make empowered decisions and get the right support for you.

Seeking help for a mental health problem

Samaritans

No matter what you or your family are going through, the Samaritans are waiting for your call. You can get in touch with them at 116 123 for free. They're open 24 hours a day, 365 days a year. Learn more about them using the link below:

Samaritans: We're waiting for your call

Shout

If you would prefer not to talk but want some mental health support, you could text SHOUT to 85258. Shout offers a confidential 24/7 text service providing support if you are in crisis and need immediate help.

Every Mind Matters

We all have mental health.  Every Mind Matters understands that. So, they've set up a website to provide you with expert advice, practical tips and support.

Every Mind Matters: Mental Health Issues

SANE provides emotional support and information to families, friends and carers over the age of 16. Offers a textcare service that allows you to arrange for messages of support at times that are right for you. Details:

www.sane.org.uk/what_we_do/support/textcare/www.sane.org.uk/what_we_do/support/textcare/

Helpline: 0300 304 7000 (4pm - 10pm every day of the year)

Website: www.sane.org.uk/

Email support: support@sane.org.uk (responses within 72hrs)

National Suicide Prevention Helpline UK

The National Suicide Prevention helpline offers a supportive listening service to anyone with thoughts of suicide. You can call the National Suicide Prevention Helpline UK on 0800 689 5652 (6pm to midnight every day). If you’re unable to connect to this number, you can call us on 0800 689 0880

Campaign Against Living Miserably (CALM)

You can call the CALM on 0800 58 58 58 (5pm–midnight every day) if you are struggling and need to talk. Or if you prefer not to speak on the phone, you could try the CALM webchat service.

Breathing Space

It helps to talk to someone when our thoughts and feelings overwhelm us. The Breathing Space helpline is open 24 hours on weekends and 6pm - 2am on weekdays. It's available for anyone in Scotland over the age of 16.  All calls are confidential 0800 83 85 87. Learn more about Breathing Space below:

NHS 24

You can call 111 or 999 or critical health support - including mental health support - outside of GP opening hours.

Additional NHS Scotland support

If you live in Scotland, and you think you or a family member may have a mental health condition but aren't sure how to identify it? NHS Inform can help you learn about various mental health conditions and the treatments available.

They also provide some fantastic self-help guides for people with mild-to-moderate mental health symptoms.

NHS Inform: Mental Health

We have now closed participant recruitment. The final deadline for sign up and questionnaire completion was 15 November 2023.

When we created the first questionnaire, there were many more questions we would like to have asked, but to keep the questionnaire to a manageable length, we decided we could not include them all.

This second questionnaire is designed to complement the first by delving deeper into your experience of ME/CFS. It asks questions suggested by people with ME/CFS, as well as standard questions previously used in other studies. These standard questions will enable useful comparisons to be made with other illnesses and populations. The answers to these questions will be useful to both the DecodeME study and other future research.