Test Catalog

Test ID: MAGES    
Myelin-Associated Glycoprotein Autoantibodies, IgM, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Evaluating peripheral neuropathy


Evaluating paraproteinemic neuropathy

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Autoantibodies directed against myelin-associated glycoprotein (MAG) are associated with sensory motor demyelinating peripheral neuropathy. A distal acquired demyelinating symmetric (DADS) neuropathy phenotype is the most commonly associated presentation. Patients typically have a slowly progressive symmetric sensory ataxia with/without distal weakness and an IgM monoclonal gammopathy of undetermined significance (MGUS). Nerve conductions studies typically demonstrate a characteristic progressive sensory predominant mixed axonal and demyelinating neuropathy with reduced distal conduction velocities that are greater distally. In general, patients with a DADS neuropathy show limited treatment responses to intravenous immunoglobulin and more aggressive immunotherapy may be needed. MAG antibody titers do not correlate with disease severity nor treatment responses. The presence of MAG antibodies is not exclusively diagnostic of an acquired neuropathy and results must be interpreted in the correct clinical and electrophysiological context. MAG antibodies are present in approximately 50% to 70% of those with an IgM M-protein and a DADS neuropathy phenotype. However, MAG antibodies may also be identified in those with an IgM M-protein and a chronic inflammatory demyelinating polyneuropathy (CIDP) presentation as well as in other IgM paraproteinemic disorders that present with neuropathy including in myeloma, lymphoplasmacytic lymphoma (Waldenstrom macroglobulinemia) and amyloid light chain (AL)-IgM primary amyloidosis. Higher MAG antibody titers (>10,000 BTU) are better predictors of an electrophysiological DADS phenotype whereas low titer MAG antibodies may be associated with a more diverse group of neuropathies. Detection of MAG IgM antibody by enzyme-linked immunosorbent assay based on human MAG (100 kDa) antigen is significantly more sensitive and specific than MAG western blot and immunofluorescence assays using primate antigen.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

<1500 Buhlmann Titer Unit

Interpretation Provides information to assist in interpretation of the test results

A positive result is consistent with anti-myelin-associated glycoprotein neuropathy.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This test is not diagnostic and should be interpreted in the correct clinical context. Myelin-associated glycoprotein antibodies may be found in those without neuropathy, IgM M-protein, or paraproteinemic neuropathy.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Kuijf ML, Eurelings M, Tio-Gillen AP, et al: Detection of anti-MAG antibodies in polyneuropathy associated with IgM monoclonal gammopathy. Neurology. 2009 Sep;73(9):688-695

2. Katz JS, Saperstein DS, Gronseth G, Amato AA, Barohn RJ: Distal acquired demyelinating symmetric neuropathy. Neurology. 2000 Feb;54(3):615-620

3. Magy L, Kabore R, Mathis S, et al: Heterogeneity of polyneuropathy associated with anti-MAG antibodies. J Immunol Res. 2015;2015:450391