STAT4 and rheumatoid arthritis: RA genetics has been studied mainly in underpowered candidate gene association studies in Northern and Southern Africa, and there have been few reports in Tunisia (PTPN22 [10,11], TNFAIP3 [12], STAT4 [13], IRF5 [14], DNASE1 [15], SUMO4 [16], and SLAMF1 [17]), Morocco (HLA [18]), Egypt (PADI4 [19], TRAF1/C5, and STAT4 [20]), and South Africa (HLA [21], IL-10 [22], and p53 [23]).