title: Letter: Ankylosing spondylitis, sacroiliitis, regional enteritis, and HL-A 27.
mesh_terms: D000328:Adult; D003424:Crohn Disease / Q000150:complications / Q000276:immunology*; D005260:Female; D006649:Histocompatibility Antigens / Q000302:isolation & purification*; D006801:Humans; D007592:Joint Diseases / Q000150:complications / Q000276:immunology*; D008297:Male; D012446:Sacroiliac Joint; D013167:Spondylitis, Ankylosing / Q000150:complications / Q000276:immunology*
chemical_list: D006649:Histocompatibility Antigens