B3GALNT1 (Beta-1,3-N-Acetylgalactosaminyltransferase 1) is an enzyme that plays a key role in glycosylation, a process essential for proper protein function. It helps produce specific glycan structures important for cell-cell adhesion and signaling. Mutations in B3GALNT1 can cause muscular dystrophy-dystroglycanopathy, a group of disorders that impact muscle function.