In conclusion, −1123G>C and +1858C>T PTPN22 SNPs are in strong linkage disequilibrium and (−1123C/+1858T) haplotype, which comprises polymorphic variants from both polymorphisms, is associated with susceptibility to RA but is not associated with status or higher levels of anti-CCP antibodies in a Western Mexican population. Here, PTPN22 is linked to rheumatoid arthritis.