title: Letter: HLA-B27 and modified bone formation.
mesh_terms: D005097:Exostoses, Multiple Hereditary / Q000276:immunology*; D006680:HLA Antigens; D006649:Histocompatibility Antigens; D006801:Humans; D013167:Spondylitis, Ankylosing / Q000276:immunology*
chemical_list: D006680:HLA Antigens; D006649:Histocompatibility Antigens