Ehlers-Danlos syndrome (EDS) is not an autoimmune disease. It is a group of inherited connective tissue disorders caused by genetic mutations that affect how your body builds or processes collagen, the protein that gives structure to skin, joints, blood vessels, and organs. Unlike autoimmune diseases, where the immune system mistakenly attacks healthy tissue, EDS results from a structural defect that’s present from birth.
That said, the line between EDS and autoimmune conditions is blurrier than it first appears. People with EDS are diagnosed with autoimmune and inflammatory diseases at higher rates than the general population, and recent research suggests the most common form of EDS may involve immune system changes that science is only beginning to understand.
Why EDS Is Classified as Genetic, Not Autoimmune
There are currently 13 recognized subtypes of EDS, and for most of them, researchers have identified specific mutations in genes that either encode collagen directly or encode the enzymes that modify it. Classical EDS, for example, results from mutations in genes responsible for type V collagen. These mutations can take many forms: some prevent one copy of the gene from producing a functional protein at all, while others produce abnormal collagen molecules that disrupt the structure of the triple helix shape collagen needs to function properly.
Vascular EDS involves defects in type III collagen, which is critical for the integrity of blood vessels and organs. These mutations slow collagen production or render the final protein nonfunctional. In every case, the problem is baked into the DNA. Your body simply cannot make collagen correctly.
Autoimmune diseases work differently. In conditions like rheumatoid arthritis or lupus, the immune system produces antibodies that target the body’s own tissues, causing inflammation and damage over time. This process shows up on blood tests as elevated autoantibodies, inflammatory markers, or specific immune proteins. EDS does not involve this kind of immune-mediated attack. As one review in the Journal of Translational Autoimmunity put it, “there has yet to be a clearly defined role of the immune system in any of the subtypes of EDS.”
How EDS Gets Confused With Autoimmune Conditions
The confusion is understandable. EDS causes chronic joint pain, fatigue, and widespread body symptoms that look a lot like what autoimmune diseases produce. Many people with EDS spend years seeing rheumatologists and getting tested for lupus, rheumatoid arthritis, or other inflammatory conditions before landing on the correct diagnosis. Both EDS and autoimmune diseases are often managed by the same specialists, which adds to the overlap in perception.
The diagnostic criteria for hypermobile EDS (hEDS), the most common subtype, are entirely clinical. There is no blood test or genetic marker for it. Diagnosis relies on documented joint hypermobility, physical signs of connective tissue involvement (such as unusually soft skin, stretch marks without an obvious cause, hernias, or dental crowding), and exclusion of other conditions. No autoimmune markers like antinuclear antibodies or rheumatoid factor are part of the criteria.
Autoimmune Diseases Are More Common in People With EDS
While EDS itself is not autoimmune, people who have it are significantly more likely to also have autoimmune or inflammatory conditions. A study published in Scientific Reports found that when hEDS patients received comprehensive workups, a wide range of inflammatory diseases appeared at rates well above what you’d expect in the general population. The most common were fibromyalgia and psoriasis (22 cases each in the study group), followed by ankylosing spondylitis and psoriatic arthritis (11 cases each), and rheumatoid arthritis (9 cases). Rarer findings included lupus, autoimmune thyroiditis, Crohn’s disease, celiac disease, Sjögren’s disease, and pernicious anemia.
Fifteen of these conditions were significantly more prevalent in EDS patients than in the general population. This wasn’t a coincidence of overlapping symptoms. Many of these diagnoses required extensive bloodwork and imaging to confirm.
Why this overlap exists isn’t fully understood. One possibility is that defective connective tissue creates an environment of chronic low-grade stress in the body that tips a genetically susceptible immune system toward dysfunction. Another is that shared regulatory pathways connect collagen integrity and immune signaling in ways researchers haven’t fully mapped yet.
Mast Cell Problems and the Immune Connection
Many people with hEDS also develop mast cell activation syndrome (MCAS), a condition where mast cells (immune cells found throughout your tissues) release their chemical contents too easily or too often. This causes episodes of flushing, hives, gastrointestinal distress, rapid heart rate, and sometimes anaphylaxis-like reactions. MCAS is not technically autoimmune either, but it represents a real form of immune dysfunction.
The connection between mast cells and connective tissue may be more than coincidental. Mast cells release chemicals, including histamine and an enzyme called tryptase, that directly influence fibroblasts (the cells that build collagen) and stimulate collagen production. In people with already-abnormal connective tissue, this chronic mast cell activity may create a feedback loop of inflammation and tissue disruption. The overlap between MCAS symptoms and hEDS symptoms is so extensive that some researchers suspect mast cell dysfunction could help explain many of the seemingly unrelated problems hEDS patients experience across multiple organ systems.
This triad of hEDS, MCAS, and POTS (postural orthostatic tachycardia syndrome, a condition affecting heart rate and blood pressure regulation) is widely recognized in clinical practice, though the biological mechanism linking all three remains an active area of investigation.
New Research Challenges the Old View
A 2025 proteomic study published in ImmunoHorizons has added an unexpected layer to this picture. Researchers compared blood proteins in hEDS patients to healthy controls and found a distinct pattern of immune dysregulation. Surprisingly, the classical structural collagen proteins were not significantly different between the two groups. Instead, what stood out were consistent reductions in complement system components, proteins that form a key part of your innate immune defense.
The study found reduced levels of complement proteins across multiple pathways, including C1QA (part of the classical pathway), C3 (a central hub of complement activation), and several terminal components like C8A, C8B, and C9. These reductions held up regardless of age, sex, or whether the patient had a separate autoimmune diagnosis. The researchers also found changes in profibrotic cytokines, signaling molecules that promote tissue scarring and remodeling.
These findings led the authors to propose that hEDS may not be purely a structural collagen disorder. Instead, innate immune dysfunction could be contributing to the widespread, multi-system nature of the condition. This doesn’t reclassify EDS as autoimmune, but it does suggest that immune involvement may be part of the story, particularly for the hypermobile subtype where no causative gene has been identified.
What This Means for You
If you have EDS and are experiencing symptoms that seem immune-related, such as reactions to foods or environmental triggers, unexplained rashes, joint inflammation that feels different from your usual hypermobility pain, or symptoms that fluctuate with illness or stress, it’s worth pursuing evaluation for co-occurring conditions like MCAS or specific autoimmune diseases. The research makes clear that these aren’t rare coincidences in the EDS population.
EDS is genetic. You’re born with it, and it doesn’t involve your immune system attacking your own tissues the way lupus or rheumatoid arthritis does. But your immune system may not function entirely normally either, and the conditions that cluster alongside EDS are real, diagnosable, and treatable on their own terms. Getting the classification right matters because the treatments are fundamentally different: autoimmune diseases respond to immune-suppressing therapies, while EDS management focuses on protecting joints, managing pain, and preventing complications from fragile tissue.