For example, the HLA-DQB1*03/DQA1*03 and HLA-DRB1*04 alleles are associated with a higher RF prevalence, whereas HLA-DQB1*0501/DQA1*01 and HLA-DRB1*10 alleles seem to confer a protective effect against RA by reducing RF positivity (30). Here, HLA-DRB1 is linked to rheumatoid arthritis.