Genes, Environment and Your Arthritis
Want to know what triggers the swelling in your joints? So do researchers.
By Marie Karns
“Why me?” We all have asked that question at one point or another. “Why was I the one to get arthritis?”
Research is showing some clear cause-and-effect correlations for osteoarthritis, where such things as prior injury, repetitive motion and being overweight are increasingly emerging as risk factors. But the picture for autoimmune and inflammatory forms of arthritis, such as rheumatoid arthritis (RA), lupus, ankylosing spondylitis and myositis, appears to be much more complex.
Are these diseases the result of nature or nurture? Are genetics or environmental factors more influential? To find out, Arthritis Today dug beyond the standard assumptions. We read up on the latest studies and talked to some prominent arthritis researchers.
Learn what they know now about how your genes control your immune system and how the substances that enter your body – whether by your choice or by chance – affect your genes. This knowledge just may give you the power to take back some of the control you thought you had lost.
Clue 1: In Your Genes
Each of us is born with a unique genetic architecture that provides the blueprint for our physical being. For years, scientists have been trying to unravel this complex human genetic code, which contains some 3 billion bits of information. (See “What Is a Gene?”)
“About 3 million bits, or 0.1 percent [of the human genetic code], are different among unrelated people,” says Peter Gregersen, MD, an Arthritis Foundation-funded researcher at the Feinstein Institute for Medical Research, in Manhasset, N.Y., and principal investigator of the North American Rheumatoid Arthritis Consortium (NARAC).
The keys to unraveling how certain genes predispose or protect a person from inflammatory arthritis lie in the variations of those 3 million bits. Researchers are uncovering an increasingly clear connection between a select few of these unique genetic pieces and the likelihood of a person developing autoimmune or inflammatory forms of arthritis.
As far back as the 1970s, scientists found that a specific genetic component known as the human leukocyte antigen (HLA) was connected to RA. The HLA helps the body’s immune system recognize which cells are “self” and which cells are foreign. More recently, certain variations or defects in HLA have been found to prime the body to attack itself – the hallmark feature of autoimmune disease.
What the Future Holds
With today’s advanced gene-processing technology, Dr. Gregersen predicts that most of the genetic variations that are linked to RA will be identified in approximately two to three years, including variants that may run in certain families, ethnic populations or geographical regions.
Knowing which genetic variants an individual has, a rheumatologist will be able to tailor drug treatments accordingly. For example, right now, 20 to 30 percent of people with RA who try the biologic drugs called tumor necrosis factor (TNF) inhibitors have no response, but there’s no way to tell who will respond to the drugs and who won’t, says Dr. Gregersen. In five to 10 years, a rheumatologist may be able to consult a patient’s genetic map to determine which drug would be the most effective, without engaging in treatment trial and error.
Further down the line, gene therapy still holds promise as a way of correcting problems caused by faulty genes. Repairing the genes would mean the underlying problem, and the need for medicine to treat it, would be eliminated. Work continues to find the best techniques for implanting DNA that would deliver the proper genes to the right place.
Next: Smoking Can Set Off Flares
