Costenbader KH, Chang SC, Laden F et al.
Brigham and Women’s Hospital, Boston, MA, USA.
Arch Intern Med 2008;168:1664–70.
Editor’s note: As knowledge about thegenetic risk factors for rheumatoid arthritis (RA) advances at a pace, there is a pressing need for further studies to identify environmental triggers for RA. A number of risk factors are already known, such as cigarette smoking, obesity, and lack of exposure to the oral contraceptive pill.