Genetic Factors for the Severity of ACPA-negative Rheumatoid Arthritis in 2 Cohorts of Early Disease: A Genome-wide Study.

de Rooy DP, Tsonaka R, Andersson ML, Forslind K, Zhernakova A, Frank-Bertoncelj M, de Kovel CG, Koeleman BP, van der Heijde DM, Huizinga TW, Toes RE, Houwing-Duistermaat JJ, Ospelt C, Svensson B, van der Helm-van Mil AH. J Rheumatol. 2015 Aug;42(8):1383-91.