The results of a genetic screening both confirmed two previous genetic variations associated with rheumatoid arthritis (RA) and discovered two new genes, according to a consortium of researchers. The results are presented in two articles in the New England Journal of Medicine.
A team of researchers led by professors at the Karolinska Institute, together with others at the Genome Institute of Singapore, compared the genomes of over 15,000 rheumatics with those of 1,850 controls. Their analysis showed that the DNA of these two groups are at a variance at three sites—two genes previously linked to the disease, HLA-DRB1 and PTPN22, and a previously unresearched gene complex known as TRAF-C5, all three are associated with immune cells.
The Swedish researchers and investigators from the Intramural Research Program also used the same material to examine the variants within 13 candidate genes located in a region of chromosome 2, which they had previously linked with RA. They found that another gene, STAT 4, was also related to the disease and immune cells. Replicating the result in two independent collections of RA cases and controls, one variant form of the gene was present at a significantly higher frequency in RA patient samples from the North American Rheumatoid Arthritis Consortium as compared with controls, according to the investigators.
The team also found that the same variant of the STAT4 gene was even more strongly linked with lupus in three independent collections of patients and controls. Frequency data on the genetic profiles of the patients and controls reportedly suggest that individuals who carry two copies of the disease-risk variant form of the STAT4 gene have a 60% increased risk for RA and more than double the risk for lupus compared with people who carry no copies of the variant form.