Unknown / idiopathic trigger

DecodeME ME/CFS GWAS preprint not peer-reviewed

Registry linkage · N=15579 · control Unexposed (unmatched) · 0 obs · max follow-up n/r mo

Measures: no observations yet

The largest ME/CFS genome-wide association study (15,579 cases). Included as the anchor host-genetic susceptibility cohort for an idiopathic syndrome: eight genome-wide signals, of which four (RABGAP1L, FBXL4, OLFM4, CA10) replicated in independent post-exertional-malaise/fatigue samples. Genetic factors are temporality-valid by construction (fixed at conception). Initial findings are a 2025 preprint — flagged accordingly.

NIH Intramural ME/CFS Deep-Phenotyping Study (Walitt/Nath 2024) small sample

Cross-sectional · N=57 · control Healthy convenience · 6 obs · max follow-up 0 mo

Measures: 2-day CPET workload drop, Fatigue, Institute of Medicine / NAM ME/CFS criteria (IOM 2015), Post-exertional malaise, Tilt-table haemodynamic response

The single most intensively measured ME/CFS cohort in existence. 17 ME/CFS participants (IOM 2015 criteria) and 21 matched healthy controls underwent an exhaustive multi-day protocol at the NIH Clinical Center including: 2-day CPET, tilt-table testing, brain MRI/MRS, fMRI, metabolomics, proteomics, immunophenotyping (flow cytometry, CyTOF, cytokine panels), stool microbiome, muscle biopsy with RNA-seq and mitochondrial respirometry, CSF lumbar puncture with proteomics and metabolomics, overnight polysomnography, and extensive neuropsychological testing. Despite the small N (~40), this is the highest-value Tier-1 cohort for physiologic and lab measures. The study found no consistent immunological signature discriminating cases from controls but documented significant effort preference and central motor activation differences. Placed under unknown-trigger as participants had both post-infectious and gradual onset. A contested study in the patient community due to the interpretation of the CPET and effort-preference findings; the database records the observations regardless of interpretive controversy.

UK ME/CFS Biobank (CureME, LSHTM)

Cross-sectional · N=632 · control Other-disease · 5 obs · max follow-up n/r mo

Measures: Fatigue, Fukuda/CDC 1994 CFS criteria, Post-exertional malaise, Sleep disturbance

The largest deeply phenotyped ME/CFS biobank with matched healthy and multiple sclerosis disease controls. Participants were clinically assessed and met both Fukuda (CDC 1994) and Canadian Consensus (CCC 2003) criteria for ME/CFS. Specimens include serum, PBMC, RNA, and whole blood — valuable for biomarker discovery. Not a prospective inception cohort; cross-sectional with retrospective illness duration data. Illness duration ranges widely (new-onset to decades). Placed under unknown-trigger as the cohort includes participants with both post-infectious and gradual onset; the database records ME/CFS as the outcome, not the trigger.