The homozygous genotype HLA-DRB1*0401/0401 was significantly more frequent in patients with Felty's syndrome (genotype frequency 0.286; P = 0.002) and patients with pericarditis (genotype frequency 0.185; P = 0.043) than in non-ExRA controls (frequency 0.068). Here, HLA-DRB1 is linked to Felty syndrome.