Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 14 4 2015 10 20 437 442 EN Somayeh Ahmadloo Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Mohsen Taghizadeh Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Mohsen Akhiani Department of Rheumatology, Alborz Hospital, Karaj, Iran. Ahmad Salimzadeh Rheumatology Research Center, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Keramatipour Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 19 2015 10 19 The rs2476601 (R620W, C1858T) polymorphism in PTPN22 gene has been repeatedly reported to be associated with rheumatoid arthritis (RA). The rs 2476601 is widely suggested for predictive testing and risk assessment for RA. The aim of this study was to test the possible association of this SNP with RA in Iranian population.A total of 872 samples (405 confirmed RA patients and 467 healthy controls) were recruited in  this  study. Genomic  DNA  was extracted  from  whole  blood  and  the  genotyping  was performed  by  polymerase  chain  reaction–restriction  fragment  length  polymorphism  (PCR- RFLP). Genotyping for a set of samples were re-confirmed by two other rounds of genotyping, using another PCR-RFLP experiment with different enzyme and DNA sequencing.All 872 samples were genotyped as homozygous CC in first round of genotyping. Genotyping was repeated for 30% of samples by another restriction enzyme and for 10% of samples by sequencing. Again all samples showed homozygous CC genotype.This study suggests that the rs2476601 polymorphism of PTPN22 gene is mono-morphic in Iranian population, containing only C allele.Considering that previous studies in other populations reported the T allele as the risk allele at this locus, the present study concluded that rs2476601 play no role in susceptibility to RA and other autoimmune diseases in Iranian population. This finding has significant future clinical implications in determining the strategy for risk assessment and predictive testing for such diseases in Iranian population. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/591 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/591/531