Many patients with rheumatic and autoimmune conditions have more than one of these ailments. Why is that?

Lupus is back in the spotlight after singer Selena Gomez announced that the disorder has caused her to cancel her latest tour.

But the condition is also in the news due to a recent report that reaffirms earlier studies that concluded patients with lupus — and related conditions like rheumatoid arthritis (RA) — are more likely to develop secondary autoimmune conditions.

This is no surprise to Macy Stephens of Nebraska.

She has long felt that autoimmune conditions can overlap or come on in clusters.

“I joke that my autoimmune illnesses are like potato chips or a Skittle. You can’t just have one. My doctor says that this is common, and I also encounter other patients online who have several [autoimmune] diseases,” she told Healthline.

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Stephens’ theory is not too far-fetched, at least according to some studies.

Researchers have suspected there is an overlap with diseases like RA, lupus, multiple sclerosis (MS), Crohn’s disease, and others.

In one study, published in 2010 in the MÆdica journal of clinical medicine, researchers reported that at least 25 percent of patients with an autoimmune disease develop a second autoimmune disorder.

This particular study noted a frequent overlap between RA and SLE (lupus).

Another 2009 report in the American Journal of Epidemiology stated that “evidence suggests that autoimmune diseases tend to co-occur, although data are needed to determine whether individuals with an existing autoimmune disorder are at increased risk of a second disorder.”

According to — a nonprofit website for patients with the autoimmune disease called scleroderma — “RA is often found in overlap with other connective tissue diseases such as scleroderma, lupus, and polymyositis/dermatomyositis. It can also be found with other diseases such as thyroiditis, fibromyalgia, and Sjogren’s.”

The Lupus Foundation of America also addresses autoimmune overlap in lupus patients, citing RA as a common one. They provide questions and answers for patients with lupus who are struggling to understand overlapping autoimmune diagnoses.

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Most researchers seem to agree, at least in theory, about the “secondary autoimmune” syndrome.

The big question for them now is: “Why does this happen?”

The theories on the causative factors for polyautoimmunity (sometimes called multiple autoimmune syndrome or autoimmune overlap disease) range from neurological to genetic to environmental.

In a nutshell, it could be anything from a faulty immune system, an impaired cellular process, a neurological malfunction, simple heredity, or lifestyle factors.

Many studies, including one from 2012, conclude there is a specific genetic component.

In a story last month on, Dr. Regina Berkovich, Ph.D., an assistant professor of clinical neurology at Keck Medicine at the University of Southern California, said she believes a faulty immune system is to blame.

“It is a case of mistaken and activated immune system,” she said. “If the immune system already follows the autoimmune pattern, it is just a higher possibility that there will be another target.”

Patients who are concerned that they may have a rheumatologic or autoimmune disease should discuss their concerns with a licensed rheumatologist to have the proper tests and evaluations done in order to form an official diagnosis.

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