HLA-DRB1 and rheumatoid arthritis: The risk varied depending on the ethnicity of the population: the highest risk was determined HLA-DRB1*04 among the Western Europe residents for the British OR = 7.02, whereas the lowest was in Asians for Pakistanis OR = 0.65, with the allele HLA-DRB1*04 being a risk factor for RA, and HLA-DRB1*13 being a protector [16].