title: Component deficiencies. 2. The fourth component.
mesh_terms: D003181:Complement C4 / Q000172:deficiency* / Q000235:genetics / Q000276:immunology; D005260:Female; D006680:HLA Antigens / Q000032:analysis; D006801:Humans; D007109:Immunity; D008297:Male; D010375:Pedigree
chemical_list: D003181:Complement C4; D006680:HLA Antigens