The GLOB system was acknowledged in 2002 when the P or globoside antigen was moved from the 209 collection. The P antigen is the most common neutral glycosphingolipid in the red cell membrane, belongs to the globoseries and has the following structure: GalNAcβ3Galα4Galβ4Glcβ1 ceramide, also known as globoside (Gb4Cer). The B3GALT3 gene was first reported in 1998 by Amado et al. to be a member of the β1,3-galactosyltransferase gene family and its product given the name β3Gal-T3. It was later shown by Okajima et al. to possess UDP-N-acetyl galactosamine:globotriaosylceramide 3-β-N-acetylgalactosaminyltransferase or globoside synthase activity and the gene name changed to B3GALNT1 and its product renamed β3GalNAc-T1. This enzyme is responsible for the final step in the synthesis of the P antigen, the transfer of GalNAc to the terminal Gal of the Pk antigen. The final proof of this was the identification by Hellberg et al. of critical mutations in the B3GALNT1 gene as the genetic basis of P1 k and P2 k , the rare globoside-deficient null phenotypes of the GLOB system.