GSTM1 and rheumatoid arthritis: Interestingly, the largest previous studies of genetic risk from GSTM1 (n the Nurese Health Study; Keenan et al (19) was also based on population-based recruitment and was not sensitive to selection on long-time severity, and this study on 549 RA cases and controls, Keenan et al. [20] could not demonstrate any association between GSTM1 and development of RA.