ABO Blood Group Antigens NAG Gal NACGA Fuc NAG Gal NAG Gal A antigen Fuc B antigen Precursor oligosaccharide Hantigen NAG Gal Gal NAcGA(N-acetylgalactoseamine) Gal (galactose) B Fuc ABO Blood Group Antigens Precursor oligosaccharide H antigen B antigen NAG Gal NAcGA Fuc NAG Gal NAG Gal Fuc H Fuc NAG Gal Gal B A A antigen NAcGA (N-acetylgalactoseamine) Gal (galactose)