GNE

GNE: An Overview

GNE, or UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase, is a bifunctional enzyme that plays a crucial role in the biosynthesis of sialic acid, an important component of glycoproteins and glycolipids in humans. Mutations in the GNE gene are associated with a rare genetic disorder known as GNE myopathy.

Structure and Function

The GNE enzyme is composed of two distinct domains:

• UDP-N-acetylglucosamine 2-epimerase domain: This domain catalyzes the conversion of UDP-N-acetylglucosamine to N-acetylmannosamine and UDP.
• N-acetylmannosamine kinase domain: This domain phosphorylates N-acetylmannosamine to produce N-acetylmannosamine-6-phosphate.

These reactions are the initial steps in the biosynthesis of sialic acid, which is essential for the proper function of various cellular processes, including cell-cell interaction, signaling, and immune response.

Genetics

The GNE gene is located on chromosome 9 (9p13.3) and consists of 13 exons. Mutations in this gene can lead to a reduction in sialic acid production, which is implicated in the pathogenesis of GNE myopathy.

GNE Myopathy

GNE myopathy, also known as hereditary inclusion body myopathy (HIBM), is an autosomal recessive disorder characterized by progressive muscle weakness and atrophy. The disease typically presents in early adulthood and primarily affects the distal muscles.

Symptoms

• Progressive muscle weakness
• Atrophy of distal muscles
• Difficulty walking
• Foot drop

Diagnosis

Diagnosis of GNE myopathy involves genetic testing to identify mutations in the GNE gene, along with muscle biopsy and clinical evaluation.

Treatment

Currently, there is no cure for GNE myopathy. Treatment focuses on managing symptoms and may include physical therapy, orthotic devices, and supportive care.

Research and Future Directions

Research is ongoing to better understand the pathophysiology of GNE myopathy and to develop potential therapies. Gene therapy and enzyme replacement therapy are areas of active investigation.

Also see

• Sialic acid
• Glycoprotein
• Glycolipid
• Muscle atrophy
• Genetic disorder