The amount of blood group A substance on platelets is proportional to the amount in the plasma.
D000017:ABO Blood-Group System / Q000235:genetics / Q000276:immunology*; D000372:Agglutination Tests; D001792:Blood Platelets / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology; D006801:Humans; D010641:Phenotype; D010949:Plasma / Q000032:analysis; D013921:Thrombocytopenia / Q000097:blood
D000017:ABO Blood-Group System