Whole-genome association studies in rheumatoid arthritis have identified 
single-nucleotide polymorphisms (SNPs) predisposing to disease with moderate 
risk. We aimed to investigate the role of these markers in predicting 
methotrexate (MTX) response, measured by continuation on MTX monotherapy in 
patients with recent onset inflammatory polyarthritis (IP). In all, 19 SNPs were 
genotyped in 736 patients treated with MTX following registration, or not more 
than 3 months before registration, to the Norfolk Arthritis Register. The 
association of SNPs with MTX continuation by year 1 and by year 2 was 
investigated using Cox proportional hazard regression models. A SNP within the 
OLIG3/TNFAIP3 locus (rs6920220) was associated with being less likely to 
maintain MTX monotherapy at year 1, hazards ratio (HR) 1.73 (1.18, 2.52) and 
year 2, HR 1.49 (1.11, 2.00); correlating with an increased in adverse events. 
Weak evidence for an effect at the PTPN22 locus was also observed. These 
findings require replication in other large datasets.