PTPN22 and rheumatoid arthritis: Interestingly, rs2488457 was recently reported as a potential cis-expression quantitative trait loci (eQTLs) in whole blood from Spanish RA patients, and another study demonstrated that PTPN22 expression is significantly decreased in whole blood from RA patients carrying the risk alleles of SNPs C1858T and G1123C compared to healthy controls [101,102].