In turn, in studies in Latin American (LA) populations with a large proportion of European ancestry some HLA-DRB1 alleles have also been associated with RA [18], and also a meta-analysis seemed to revalidate the SE hypothesis in LA populations [19,20] In spite of this, whether the association of HLA-DRB1 and RA is valid in all ethnic groups remains unclear. The gene discussed is HLA-DRB1; the disease is rheumatoid arthritis.