MAG5 Antibody

Overview of Anti-MAG Antibodies

Anti-MAG antibodies target myelin-associated glycoprotein (MAG), a glycoprotein critical for maintaining the structure and function of myelin sheaths in peripheral nerves. These antibodies are predominantly immunoglobulin M (IgM) and are strongly associated with distal acquired demyelinating symmetric (DADS) neuropathy, a rare autoimmune peripheral neuropathy often linked to IgM monoclonal gammopathy of undetermined significance (MGUS) .

Key Features:

• Pathogenic Role: Anti-MAG antibodies disrupt myelin integrity, leading to progressive sensory ataxia, distal weakness, and demyelinating nerve damage .

• Diagnostic Utility: Detected via ELISA using human MAG antigen, with higher titers (>10,000 Buhlmann Titer Units) correlating with DADS neuropathy .

• Epidemiology: Present in 50–70% of patients with IgM paraproteinemia and neuropathy .

Table 1: Association Between Anti-MAG Antibody Reduction and Clinical Outcomes

Key Observations:

• A ≥50% reduction in anti-MAG IgM titers or paraprotein levels correlates with sustained clinical improvement .

• Nonresponders show minimal antibody reduction (≤20%) and often require aggressive immunotherapy .

Diagnostic Criteria:

• Electrophysiological Findings: Progressive sensory-predominant demyelination with reduced distal conduction velocities .

• Testing Methods: ELISA assays (e.g., Mayo Clinic Laboratories’ in-house test) using human MAG antigen offer superior sensitivity over Western blot .

Treatment Insights:

• Immunotherapy: Rituximab, IV immunoglobulins (IVIg), and plasmapheresis are common, though response rates vary .

• Biomarker Utility: Anti-MAG antibody titers guide treatment decisions but do not predict disease severity .

Research Gaps and Controversies

• Heterogeneity: Anti-MAG antibodies are occasionally detected in chronic inflammatory demyelinating polyneuropathy (CIDP), complicating diagnosis .

• Titer Thresholds: Higher titers (>70,000 BTU) better distinguish DADS from CIDP .