gne

GNE, sometimes written gne in informal contexts, is a human gene that encodes a bifunctional enzyme involved in the biosynthesis of the sugar sialic acid. The enzyme plays a key role in producing sialylated glycans, which are essential components of many glycoproteins and glycolipids in cells.

Function: The GNE enzyme has two catalytic activities in a single polypeptide: UDP-N-acetylglucosamine 2-epimerase, which converts UDP-GlcNAc to N-acetylmannosamine (ManNAc), and N-acetylmannosamine kinase, which phosphorylates ManNAc to ManNAc-6-P. These steps feed into the biosynthetic pathway that generates sialic acid (N-acetylneuraminic acid).

Clinical relevance: Mutations in GNE cause GNE myopathy, also known as hereditary inclusion body myopathy with GNE mutations. This autosomal recessive distal myopathy presents with progressive weakness of distal leg muscles, often beginning in the second to fourth decade. Muscle biopsies typically show rimmed vacuoles. There is no widely approved disease-modifying therapy; research explores strategies to augment sialylation, including sialic acid supplementation or precursors.

Other notes: GNE expression is widespread in human tissues, reflecting its role in general glycoprotein and glycolipid sialylation. In non-human species, orthologs exist. The name GNE reflects its two enzymatic activities; in older literature, the term gne may appear as shorthand for the gene or enzyme.