ANN ARBOR, Mich., July 25 (UPI) -- U.S. researchers have discovered three genes that are over-expressed in rheumatoid arthritis that were not known to be associated with the disease.
University of Michigan scientists say they have also determined non-genetic factors influence the expression of these genes and the expression patterns varies between identical twins when only one twin suffered from rheumatoid arthritis. That means although identical twins share just about everything, including their genes, sometimes only one twin will have health problems when genetics predicts both of them should.
Rheumatoid arthritis is a chronic and painful inflammatory disease that results in loss of movement and bone deformities. It affects 2.1 million Americans. There are many genetic factors that put people at a high-risk for developing RA, yet only 15 percent of identical twins will both develop it.
U of M scientists compared gene expression patterns of 11 pairs of monozygotic twins who shared the same egg and were genetically identical -- but only one of them had RA. That is the first report for RA that examines gene expression patterns in monozygotic twins.
The study appears in the July issue of the journal Arthritis and Rheumatism.
