HLA-DRB1 and rheumatoid arthritis: A study conducted on RA patients in Saudi Arabia using a polymerase chain reaction sequence specific primers (PCR-SSP) method revealed that the strongest risk allele is HLA-DRB1*04 followed by HLA-DRB1*08 and HLA-DRB1*10, when compared with healthy controls (Al-Swailem et al. 2006).