The human genome has now been thoroughly screened in the hunt for the genetic causes of rheumatoid arthritis. The results, which both confirms previous hypotheses and turn the spotlight on entirely new genes, are presented in two articles in the prestigious New England Journal of Medicine.
Rheumatoid arthritis is the most common rheumatic disease, and affects approximately one per cent of the population. Its causes are unknown, but scientists believe that the chances of developing the disease are determined as much by genetic factors as they are by environment and lifestyle.
An international team of researchers from Sweden, the USA and Singapore, led by professors Lars Klareskog and Lars Alfredsson at the Swedish medical university Karolinska Institutet together with PhD group leader Mark Seielstad at the A*STAR funded national Genome Institute of Singapore, has compared the genomes of over 15,000 rheumatics with those of 1,850 controls. Their analysis shows that the DNA of these two groups are at a variance at three sites, two genes previously linked to the disease and a previously unresearched gene complex known as TRAF-C5.
The Swedish and American researchers have also used the same material to examine the significance of a specific area of the genome. They found that yet another gene, STAT 4, could be linked to the disease.
The previously studied genes and the newly discovered TRAF-C5 and STAT4 genes are each important in its own way for the function of the body's immune cells.