A weak variant of A antigen with A1 component.
D000017:ABO Blood-Group System / Q000235:genetics*; D000372:Agglutination Tests; D000818:Animals; D004912:Erythrocytes / Q000276:immunology*; D005260:Female; D006372:Helix, Snails / Q000276:immunology; D006388:Hemagglutinins / Q000276:immunology; D006801:Humans; D008297:Male; D010375:Pedigree; D012463:Saliva / Q000276:immunology
D000017:ABO Blood-Group System; D006388:Hemagglutinins