Just because someone has the genetic predisposition for Rheumatoid Arthritis (RA) it doesn't mean that it will always be expressed. There is an exciting new field in biology called epigenetics that explores the connection between the environment and the expression of certain genetic traits. In other words, it was long thought that information flowed down a oneway street from DNA to RNA to protein. In fact this concept of information flow was deemed the central dogma of biology. However, in the past few years it has been discovered that there is feedback loop beyond the random mutations of natural selection that influences whether certain genes are expressed.
This provides new hope for those carrying disease causing genes. Proponents of epigenetics such as Bruce Lipton (author of Biology of Belief) go as far as to say that since beliefs affect behavior and behavior contributes to environmental influences then changing one's beliefs and behaviors can affect how genes are expressed. Positive behaviors can then be passed down through generations much like genetic traits.
One recent study investigated the effects of environment on the expression of Rheumatoid arthritis (RA). This study conducted at the Karolinska Institutet looked at the work environment. Researchers looked at what is called psychosocial workload. In particular they found a correlation between low decision lattitude and RA.
In other words, jobs in which workers have little input in decision making had an increased incidence of RA. Lack of control in the workplace has also been associated with high blood pressure and heart attacks.
Other behavioral factors that have been associated with an increase in RA include smoking and drinking alcohol.
I think this is very exciting and I am particularly interested in how information flow to DNA can affect its expression. This study provides just one more piece to the puzzle.