Functional polymorphisms of PTPN22 and FcgR genes in Tunisian patients with rheumatoid arthritis

To investigate a possible association between functional polymorphisms of the protein tyrosine phosphatase nonreceptor type 22 (PTPN22-R620W) and receptors for the Fc fragment of IgG (FcgRIIa-H131R, FcgRIIIa-F158V FcgRIIIb-NA1/NA2), and rheumatoid arthritis (RA), 133 Tunisian patients with RA and 100 controls were genotyped. We found strong evidence of an association of PTPN22 620W allele and RA. However, analysis does not detect an association between auto-antibodies seropositivity, presence of nodules or erosions and this allele. No significant skewing of any of the three FcgR polymorphisms was seen in this RA group. Nevertheless, we identified FcgRIIIa-V/V158 as the most important FcgR genotype for severe disease subset with joint erosions and observed that patients with FcgRIIIb-NA2/NA2 genotype had an earlier incidence of clinical symptoms. In conclusion, we have confirmed that PTPN22 620W allele is associated with Tunisian RA but does not constitute a factor influencing clinical manifestations. Conversely, this study supports that the FcgRIIa/IIIa and IIIb polymorphisms could influence the course and the severity of this disease. A large number of samples are required to provide independent confirmation of these findings.