B3GALNT1 encodes beta-1,3-N-acetylgalactosaminyltransferase 1, an enzyme that transfers N-acetylgalactosamine onto globotriaosylceramide to synthesize globoside (P antigen), a major glycosphingolipid on erythrocyte membranes 1. The enzyme also synthesizes the PX2 antigen, making both P and PX2 part of the GLOB blood group system 1. Mutations in B3GALNT1 result in the rare P-deficient phenotypes (Pk, P1k, P2k), characterized by absence of functional P synthase 2. These deficiencies lead to naturally occurring anti-P and anti-PX2 antibodies that can cause hemolytic transfusion reactions and recurrent miscarriages due to cytotoxic attack on the globoside-rich fetal placenta 3 2. Globoside serves as an essential cofactor for parvovirus B19 infection, being dispensable for viral entry but required for productive infection post-entry 4. Additionally, B3GALNT1 has been identified as a potential therapeutic target in non-small cell lung cancer metastasis 5 and plays a role in cardiac remodeling, where macrophage-specific silencing improves cardiac function following myocardial infarction 6.