ME/CFS vs MCAS: symptoms, biomarkers, trials and researchliterature-only comparison
A data-driven comparison of Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) and Mast Cell Activation Syndrome (MCAS) built from the Open Source Medicine Foundation biomarker atlases, PubMed literature feeds, ClinicalTrials.gov registry extract and post-acute infection syndrome (PAIS) cohort database.
MCAS is commonly diagnosed alongside ME/CFS, and some clinicians treat the two as part of one hypermobility-dysautonomia-mast cell cluster. The evidence that mast cells drive ME/CFS symptoms is still largely observational.
No biomarker atlas exists for MCAS, so the biomarker sections below are limited to the other condition. This page compares literature, trials, therapeutics and cohorts.
What each condition is
Myalgic Encephalomyelitis / Chronic Fatigue Syndrome
Also known as: CFS, ME, Systemic Exertion Intolerance Disease
ME/CFS is a chronic, multi-system illness defined clinically by a substantial reduction in activity, post-exertional malaise (PEM), unrefreshing sleep and either cognitive impairment or orthostatic intolerance. It frequently begins after an infection, including mononucleosis (EBV), SARS, Q fever, Ross River virus and now SARS-CoV-2, but many cases have no identified trigger. There is no validated diagnostic test; research biomarkers centre on energy metabolism, immune signalling and autonomic function.
Atlas scope: Molecular, metabolic, immunological, and autonomic alterations in myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) compared to healthy sedentary and active controls — including post-exertional malaise (PEM) phenotypes.
OSMF resources: biomarker atlas · literature feed
Mast Cell Activation Syndrome
Also known as: Mast cell activation disorder
MCAS is characterised by episodic, multi-system symptoms (flushing, hives, gastrointestinal upset, wheeze, hypotension) caused by inappropriate release of mast-cell mediators, with laboratory evidence such as a rise in serum tryptase during an episode and a response to mast-cell-directed therapy. Diagnostic criteria remain contested between consensus groups. MCAS is frequently reported alongside POTS, hypermobility and post-infectious illness; OSMF follows it through a literature feed and clinical-trial registry rather than a dedicated biomarker atlas.
OSMF resources: literature feed
Side-by-side summary
| Measure | ME/CFS | MCAS |
|---|---|---|
| Biomarkers catalogued | 46 | No atlas |
| Biomarker categories covered | inflammatory (10), metabolic (10), autonomic (6), immune (5), mitochondrial (4), functional (4), autoimmune (3), neurological (2), urinary (2) | — |
| Markers with LOINC codes | 13 | — |
| Literature studies tracked | 75 | 75 |
| Most recent tracked study | 06 Jul 2026 | 10 Jul 2026 |
| Registered trials (all statuses) | 146 | 5 |
| Recruiting / not yet recruiting | 26 | 1 |
| Active, not recruiting | 9 | 0 |
| Completed | 75 | 1 |
| Terminated / withdrawn / suspended | 15 | 2 |
| Unknown status | 21 | 1 |
| Named cohorts in PAIS database | 3 | 0 |
| Therapeutic agents tracked | 179 | 11 |
Trial condition matching: ME/CFS uses the registry’s mapped condition label; MCAS uses keyword matching on registry condition and title fields. Trials listing both conditions: 1.
Biomarkers catalogued for ME/CFS
MCAS has no OSMF biomarker atlas, so no shared-marker matching is possible. The ME/CFS atlas lists 46 markers; the 15 most relevant to this comparison are shown (autonomic, immune, inflammatory and vascular categories first).
- Heart rate variability (RMSSD) Decreased autonomic
- Heart rate variability (SDNN) Decreased autonomic
- LF/HF ratio Mixed / conflicting autonomic
- Orthostatic heart rate increment Increased autonomic
- Blood pressure variability Increased autonomic
- Baroreflex sensitivity Decreased autonomic
- NK cell cytotoxicity Decreased immune
- CD8+ T cell perforin Decreased immune
- RNase L (37-kDa fragment) Increased immune
- Neutrophil elastase Increased immune
- CD26 / sCD26 (DPPIV) Mixed / conflicting immune
- Interleukin-1 (IL-1α/β) Increased inflammatory
- Transforming Growth Factor-β (TGF-β) Increased inflammatory
- Tumor Necrosis Factor-α (TNF-α) Mixed / conflicting inflammatory
- Interleukin-6 (IL-6) Mixed / conflicting inflammatory
Overlapping therapeutics under investigation (2)
Agents that appear in registered trials or the OSMF therapeutic-agent database for both ME/CFS and MCAS. Inclusion means an agent is being studied, not that it works.
- Cycling
- Swimming
Trials enrolling both conditions (1)
- NCT07454395 · Is Swimming a More Tolerable Form of Movement for Individuals With Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome? (Suspended)
Research cohorts
ME/CFS cohorts (3)
- DecodeME ME/CFS GWAS registry linkage, n=15,579, biobank active
- UK ME/CFS Biobank (CureME, LSHTM) cross sectional, n=632, biobank active
- NIH Intramural ME/CFS Deep-Phenotyping Study (Walitt/Nath 2024) cross sectional, n=57, biobank active
MCAS cohorts (0)
No named cohort for this condition in the PAIS database yet.
Recent research
Latest ME/CFS studies
Latest MCAS studies
Frequently asked questions
Can you have both ME/CFS and MCAS?
Yes. MCAS is a syndrome diagnosed on clinical criteria and can be diagnosed in someone who also has ME/CFS; 1 registered trial in the OSMF registry list both conditions, and they share 2 therapeutic agents under investigation.
How do the biomarker profiles differ?
OSMF does not maintain a biomarker atlas for MCAS, which is diagnosed by physiological or clinical criteria rather than a laboratory panel, so this is a literature-level comparison. ME/CFS has 46 catalogued markers across 9 categories (most often inflammatory, metabolic, autonomic).
Which has more active clinical trials?
ME/CFS has more: 35 active or recruiting trials versus 1 for MCAS (registry snapshot 07 Oct 2026). Totals including completed, terminated and unknown-status studies are 146 for ME/CFS and 5 for MCAS. Condition matching for MCAS relies on keyword matching of registry condition fields and may miss trials. Trial counts measure research attention, not treatment efficacy.
Which condition has more recent research?
OSMF tracks 75 recent PubMed-indexed studies for ME/CFS (latest 06 Jul 2026) and 75 for MCAS (latest 10 Jul 2026). The feeds hold a rolling window of recent publications, so they indicate current publication pace rather than lifetime output. See the ME/CFS feed and the MCAS feed for the full lists.
Are the same treatments being studied for both?
2 agents appear in the trial registry or therapeutic-agent database for both conditions, including Cycling, Swimming. All of these are investigational for these indications; none is an approved treatment for either condition. Overlap usually reflects shared hypotheses (immune modulation, autonomic support, antiviral or anti-inflammatory strategies) rather than demonstrated efficacy.
Which has larger research cohorts?
The PAIS cohort database lists 3 named cohorts for ME/CFS and 0 named cohorts for MCAS, the largest being DecodeME ME/CFS GWAS (15,579 enrolled). Cohorts with stored biospecimens and open external access are the most useful for cross-condition biomarker validation.
Related comparisons
Cite this page
@misc{osmf_mecfs_vs_mcas,
author = {Open Source Medicine Foundation},
title = {ME/CFS vs MCAS: symptoms, biomarkers, trials and research compared},
year = {2026},
howpublished = {\url{https://research.opensourcemed.info/compare/me-cfs-vs-mcas.html}},
note = {Data as of 2026-10-07}
}Get OSMF research updates
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Last updated 07 Oct 2026 (page build). Underlying data: literature feeds 06 Jul 2026 / 10 Jul 2026; trial registry 07 Oct 2026; atlases 29 Jun 2026 / n/a. Generated by scripts/build_compare_pages.py.