GSTM1 and rheumatoid arthritis: We found an increased risk of developing ACPA-positive RA in non-smoking older females carrying GSTM1 (OR: 2.12 95% CI: 1.14–3.95) as well as a trend in older females lacking the SE (OR: 2.02 95% CI: 0.98–4.16), thereby partly confirming some of the findings from Criswell et al in our larger study population.