title: Rheumatoid factor negative (seronegative) rheumatoid arthritis: evolving clinical classification and immunogenetic associations.
authors.affiliation: Department of Medicine, University of Illinois College of Medicine, Peoria 61656.
authors.forename: A T
authors.initials: AT
authors.lastname: Masi
mesh_terms: D001172:Arthritis, Rheumatoid / Q000145:classification / Q000235:genetics / Q000276:immunology*; D006684:HLA-DR Antigens / Q000032:analysis / Q000235:genetics; D015804:HLA-DR4 Antigen; D006801:Humans; D007125:Immunogenetics; D012217:Rheumatoid Factor / Q000032:analysis* / Q000235:genetics
chemical_list: D006684:HLA-DR Antigens; D015804:HLA-DR4 Antigen; D012217:Rheumatoid Factor