The largest genetic study of fibromyalgia to date has identified significant overlap with chronic pain, PTSD, and irritable bowel syndrome, as well as an unexpected link to Huntington’s disease.
New research suggests that fibromyalgia is fundamentally a disorder of pain processing within the central nervous system and may share underlying biological mechanisms with a range of chronic pain, psychiatric, and somatic conditions.
Published in Nature Medicine, the international genome-wide association study analysed genetic data from more than 2.56 million adults across 11 cohorts from the US, UK, Finland, Estonia, Denmark, and Iceland. This included 54,629 people diagnosed with fibromyalgia.
By analysing millions of genetic variants across the genomes of participants, researchers identified 26 regions associated with fibromyalgia susceptibility, including genes involved in brain development, neuronal signalling, synaptic function, pain processing, and gut-brain communication.
Fibromyalgia affects an estimated 2% of the global population and is characterised by widespread pain and tenderness, fatigue, sleep disturbance, cognitive dysfunction, and mood symptoms. Despite its prevalence, its biological basis has remained uncertain, contributing to longstanding controversy around diagnosis and management.
“For decades, patients have been dismissed or told their pain is simply psychological. Our findings confirm the condition has a clear biological basis,” said Dr Michael Wainberg, co-senior author and assistant Professor at the Institute of Medical Science, University of Toronto.
Several of the genes identified in the analysis have established roles in neural function, such as CELF4 (which regulates neuronal excitability and pain sensitivity), DRD2 (encoding the dopamine D2 receptor involved in motivation, cognition, sleep, and psychiatric disorders), DCC (which guides neural development and axonal organisation), and MDGA2 (which regulates synaptic organisation and excitatory neurotransmission).
The findings support the central sensitisation model of fibromyalgia, in which abnormal processing of sensory information within the central nervous system amplifies pain perception.
The strongest genetic association identified in the study was a common coding variant in the HTT gene. Unlike the rare mutation that causes Huntington’s disease, this variant was associated with approximately 9% higher odds of developing fibromyalgia.
Additionally, researchers identified an association near GPR52, a brain-specific receptor that regulates HTT levels and is being investigated as a therapeutic target for Huntington’s disease. The authors said this raises the possibility that drugs being developed for Huntington’s disease could eventually have relevance for fibromyalgia.
The study also found extensive genetic overlap between fibromyalgia and other common conditions.
The strongest correlations were with other chronic pain disorders, such as low back pain (genetic correlation [rg, where +1 indicates the genetic influences on the two conditions are essentially identical and 0 means there is no detectable shared genetic basis] 0.75), joint pain (0.81), myalgia (0.82), cervicobrachial syndrome (0.87), and migraine (0.61).
There were also substantial genetic correlations with psychiatric disorders such as post-traumatic stress disorder (0.78), depression (0.63), anxiety (0.46), and insomnia (0.47), as well as gastrointestinal disorders such as irritable bowel syndrome (0.70).
The authors proposed that these conditions may share a central nervous system vulnerability that predisposes individuals to both pain amplification and affective dysregulation, possibly helping to explain why fibromyalgia frequently presents alongside IBS, anxiety, depression, sleep disturbance, and trauma-related disorders.
The study also provided evidence against the view that fibromyalgia is primarily an autoimmune disorder, instead suggesting that fibromyalgia is predominantly a disorder of neural function and sensory processing.
Researchers found no significant genetic signal in the major histocompatibility complex (MHC) region – a part of the genome strongly associated with many autoimmune diseases – and no enrichment of heritability within peripheral immune cells. This suggests that fibromyalgia’s genetic risk is not primarily driven by immune or autoimmune mechanisms.
Although modest genetic correlations with rheumatoid arthritis (0.33), Sjögren’s syndrome (0.39), psoriasis (0.29), and autoimmune hypothyroidism (0.21) were observed, these were substantially weaker than the correlations with pain and psychiatric disorders.
“These findings establish a firm biological basis for a long-debated condition,” the authors wrote.
“The genetic underpinnings of fibromyalgia are shared with a remarkably wide variety of other disease types. Genetic correlations implicate digestive, genitourinary, and respiratory systems.
“One explanation is that fibromyalgia genetics captures a transdiagnostic central nervous system vulnerability that predisposes individuals to sensory and affective dysregulation. This vulnerability might manifest clinically as fibromyalgia, irritable bowel syndrome, post-traumatic stress disorder, or a constellation of other disorders, depending on other genetic and environmental factors.”
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Another notable finding was that, despite women accounting for 87.7% of cases in the study, the genetic architecture of fibromyalgia was almost identical between men and women. The genetic correlation between sexes was statistically indistinguishable from perfect correlation.
This suggests that the marked female predominance is unlikely to be explained by sex-specific genetic variants and may instead reflect hormonal influences, environmental factors, or diagnostic differences.
The authors highlighted two potential therapeutic targets identified by their research.
“The linked associations of HTT and its regulator GPR52 highlight a clear repurposing opportunity, as GPR52 is already an investigational drug target for Huntington’s disease,” they wrote.
“[Also], our association with CELF4 supports developing CELF4-based gene therapies – already under investigation for chronic pain – for fibromyalgia in particular. These loci represent genetically supported molecular targets for fibromyalgia.”
Although the findings do not yet provide a diagnostic genetic test or a new treatment, they offer one of the clearest biological frameworks yet for understanding fibromyalgia and its frequent overlap with other chronic pain and psychiatric conditions.
