Treatment strategies blocking tumor necrosis factor (anti-TNF) have proven very 
successful in patients with rheumatoid arthritis (RA), showing beneficial 
effects in approximately 50-60% of the patients. However, a significant subset 
of patients does not respond to anti-TNF agents, for reasons that are still 
unknown. The aim of this study was to validate five single nucleotide 
polymorphisms (SNPs) of PTPRC, CD226, AFF3, MyD88 and CHUK gene loci that have 
previously been reported to predict anti-TNF outcome. In addition, two markers 
of RA susceptibility, namely TRAF1/C5 and STAT4 were assessed, in a cohort of 
anti-TNF-treated RA patients, from the homogeneous Greek island of Crete, 
Greece. The RA patient cohort consisted of 183 patients treated with either of 3 
anti-TNF biologic agents (infliximab, adalimumab and etanercept) from the Clinic 
of Rheumatology of the University Hospital of Crete. The SNPs were genotyped by 
TaqMan assays or following the Restriction Fragments Length Polymorphisms 
(RFLPs) approach. Disease activity score in 28 joints (DAS28) at baseline and 
after 6 months were available for all patients and analysis of good versus poor 
response at 6 months was performed for each SNP. None of the 7 genetic markers 
correlated with treatment response. We conclude that the gene polymorphisms 
under investigation are not strongly predictive of anti-TNF response in RA 
patients from Greece.