Scientists have found a genetic link between fibromyalgia, a long-term condition that causes severe brain fog, fatigue and widespread pain, and Huntington's disease, a fatal inherited disorder that destroys nerve cells in the brain.
Around 7,000 people in the UK live with Huntington's disease, which robs patients of their ability to move, think and control their behavior. Charities estimate that up to three million UK adults may have fibromyalgia, with thousands more undiagnosed.
A team of global researchers found the link after analyzing genetic data from more than 2.5 million adults, including around 55,000 with fibromyalgia. They identified 26 genetic changes linked to fibromyalgia, many of them tied to brain and nervous system function.
The strongest signal was found within the huntingtin, or HTT, gene, the same gene that causes Huntington's disease when faulty. Scientists first identified the HTT gene as the cause of Huntington's around 30 years ago. The findings were published in Nature Medicine.
Michael Wainberg, an investigator at the Lunenfeld-Tanenbaum Research Institute and the University of Toronto and co-senior author on the paper, said the work changes how researchers think about fibromyalgia at a fundamental level.
"For decades, patients have been dismissed or told their pain is simply psychological. Our findings confirm the condition has a clear biological basis," Wainberg said.
The researchers said their findings suggest fibromyalgia may be a disorder of the nervous system rather than an autoimmune disease. That contrasts with a 2021 study by King's College London, which suggested many fibromyalgia symptoms are caused by proteins that make pain-sensing nerves more active. That study concluded fibromyalgia is a disease of the immune system, rather than the currently held view that it originates in the brain.
Who fibromyalgia affects
Fibromyalgia most commonly affects middle-aged women and is most often diagnosed after age 25. Charities estimate that between 1.8 million and 2.9 million people have the condition, and experts separate from the studies say the true number could be higher because it is often hard to diagnose.
The NHS says symptoms vary from person to person, but the most common is widespread pain. The condition can also cause extreme sensitivity to pain and bright lights, as well as stiffness. One of the most commonly reported symptoms is so-called "fibro fog," in which people struggle to remember, concentrate and even speak.
The new research also found strong links between fibromyalgia and other conditions including back pain, irritable bowel syndrome and post-traumatic stress disorder. The researchers believe these conditions may share underlying problems in the nervous system, which could explain why they often occur together.
Frances Williams, a rheumatologist at TwinsUK, King's College London and a co-author on the study, said chronic pain syndromes are known to cluster together in individuals and families and are genetically similar.
"Targeting the shared mechanisms underlying them could potentially benefit a whole cluster of disorders," Williams said.
Despite the genetic links, the researchers stressed that genes alone are unlikely to explain why someone develops fibromyalgia. Instead, they believe other triggers, such as a painful condition like arthritis, may be needed before the illness develops.
Nasa Sinnott-Armstrong, of Fred Hutch Cancer Center and the University of Washington in Seattle, said understanding how genes, environmental exposures and life events jointly contribute to fibromyalgia risk is critical.
"Further research into triggers of fibromyalgia and corresponding changes to neural tissues will help understand what drives fibromyalgia and how to treat it," Sinnott-Armstrong said.
The team also found no genetic differences between men and women, despite fibromyalgia being diagnosed around three times more often in women.
