Objective    To investigate the correlation between the peptidylarginine deiminase 4 (PADI4) gene polymorphism and rheumatoid arthritis (RA) in Han population from Chongqing.     Methods    Blood samples of 302 identified RA patients hospitalized in our department from June 2006 to October 2007 and 322 matched normal controls were collected. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) was used to detect the PADI4 rs874881 single nucleotide polymorphisms. Rheumatoid factor (RF)

anti-cyclic citrullinated peptide (CCP) antibody and anti-keratin antibody (AKA) were also detected.     Results    Two alleles

a wild type C and a variant allele G were identified in the PADI4 rs874881. The genotype frequencies of C/C

C/G and G/G were 0.332

0.488

and 0.180 respectively in the normal controls and 0.295

0.474

and 0.232 respectively in the RA population. The distribution of the PADI4 rs874881 allele frequencies in Chongqing Han population was in consistence with Hardy-Weinberg equilibrium. There was no statistical difference in the frequencies of PADI4 rs874881 between RA and normal controls. No association was found when patients were classified according to the positive rates of RF

anti-CCP and AKA.     Conclusion    The polymorphism of the PADI4 rs874881 is not associated with rheumatoid arthritis in Han population from Chongqing. No Statistical difference is found between the PADI4 rs874881 polymorphisms and the positive rates of RF

anti-CCP and AKA in RA patients.