Doctor after doctor misdiagnosed or shrugged off Ruth Wilson’s rashes, swelling, fevers and severe pain for six years. She saved her life by begging for one more test in an emergency room about to send her home, again, without answers.

That last-ditch test found the Massachusetts woman’s kidneys were failing. The culprit? Her immune system had been attacking her own body all that time and nobody caught it.

“I just wish there was a better way that patients could get that diagnosis without having to go through all of the pain and all of, like, the dismissiveness and the gaslighting,” she said.

Wilson has lupus, nicknamed the disease of 1,000 faces for its variety of symptoms — and her journey offers a snapshot of the dark side of the immune system. Lupus is one of a rogues’ gallery of autoimmune diseases that affect as many as 50 million Americans and millions more worldwide – hard to treat, on the rise and one of medicine’s biggest mysteries.

Now, building on discoveries from cancer research and the COVID-19 pandemic, scientists are decoding the biology behind these debilitating illnesses. They’re uncovering pathways that lead to different autoimmune diseases and connections between seemingly unrelated ones – in hopes of attacking the causes, not just the symptoms.

It’s a daunting task. That friendly fire ravages nerves in multiple sclerosis, inflames joints in rheumatoid arthritis, dries out the eyes and mouth in Sjögren’s disease, destroys insulin production in Type 1 diabetes, weakens muscles in myositis and myasthenia gravis — and in lupus, it can cause body-wide havoc.

The list goes on: A new count from the National Institutes of Health tallied 140 autoimmune conditions, many rare but altogether a leading cause of chronic disease that’s often invisible.

“You look normal.