B3GALNT1 (Beta-1,3-N-Acetylgalactosaminyltransferase 1) is an enzyme that plays a crucial role in glycosylation, a process vital for proper protein function. It aids in the synthesis of specific glycan structures important for cell-to-cell adhesion and signalling. Mutations in B3GALNT1 can lead to muscular dystrophy-dystroglycanopathy, a group of disorders affecting muscle function.