Recruitment and methodology

DNA Analysis

We chose to look at DNA because significant differences between the DNA of people with ME/CFS and healthy controls must reflect biological causes of the illness. Unlike studying other biological molecules, everyone keeps the same DNA they were born with, meaning that any DNA difference linked to the disease must be a cause, not an effect.

Our study of ME/CFS was a genome-wide association study (GWAS) - a very large genetic study that aimed to uncover some of the biological roots of disease. A GWAS looks at the human genome to find where individual letters of DNA code can vary from person to person, sites called single nucleotide polymorphisms (SNPs). 

We collected saliva samples from over 18,000 participants in our cohort who met our criteria and extracted their DNA from the saliva. This was then sent for genotyping before arriving at the University of Edinburgh for thorough analysis. 

Our GWAS compared the SNPs in people with ME/CFS to healthy controls using data sourced from UK Biobank, searching for small differences between the large populations. 

You can read our analysis plan in full here

Questionnaires 

Our cohort also took part in two questionnaires over the course of the study, gathering data on lived experience, symptoms, treatments, onset and demographics. 

Read our findings from the first questionnaire 

Find out the results of our GWAS DNA analysis

Recruitment

From the beginning of DecodeME, we knew we needed to recruit a large sample size. A GWAS looks for small differences in DNA, so for these differences to be revealed on a statistically significant scale, we needed very large samples to get robust results.

Our cohort is the largest in the world, made up of 27,000 people with ME/CFS from across the UK. 

We used a variety of methods to reach people with ME/CFS and to make participation accessible for as many people as possible. 

Outreach through social media, ambassadors, charities and support groups helped us recruit these large numbers. Our Public and Patient Involvement (PPI) Group and affiliation with the 25% Group helped us make participation accessible for people with severe ME. Without this large amount of data, our study wouldn’t have been possible. Many of our participants went to great lengths to take part, managing their symptoms alongside participation and we thank them for this.