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Test Code IGG_M IgG Monosialo GM1, Serum


Specimen Required


Only orderable as part of a profile. For more information see GM1B / Ganglioside Antibody Panel, Serum.

 

Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 1 mL


Useful For

Supporting the diagnosis of an autoimmune neuropathy

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
IGMTS IgG Monos GM1 Titer, S No No

Testing Algorithm

IGG_M is screened at 1:2000, if positive titer will be performed at an additional charge.

Method Name

Only orderable as part of a profile. For more information see GM1B / Ganglioside Antibody Panel, Serum.

 

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

IgG Monos. GM1

Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  72 hours

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Clinical Information

Neuropathy patients have variable sensory disturbance (loss or exaggerated sensation including with pain), weakness and autonomic involvements (sweat abnormalities, gastrointestinal dysfunction, and lightheadedness on standing). These symptoms are a result of injury to the distal nerves, roots, and ganglia or their gathering points (nerve plexus in the thighs and arms). Patients may have symmetric or asymmetric involvements of the extremities, trunk, and head including extraocular muscles. Subacute onsets and asymmetric involvements favor inflammatory or immune causes over inherited or metabolic forms. Depending on the specific inflammatory or immune mediated causes other parts of the nervous system may also be affected (brain, cerebellum, spinal cord). Nerve conductions and needle electromyography can help to classify the neuropathy as either: 1) primary axonal; 2) primary demyelinating; or 3) mixed axonal and demyelinating.

 

Among the immune-mediated peripheral neuropathies, autoantibodies to gangliosides represent an important class of noncancer-associated autoimmune peripheral neuropathies. Gangliosides are glycosphingolipids that contain sialic acid and are present in many cell types most abundantly within neural tissues along their linings (myelin). Depending on the specific ganglioside autoantibody found and the antibody titer, in the appropriate clinical context, these findings may be supportive of a specific clinical diagnosis and may also be prognostic for treatment response.(1,2)

 

Specifically, in multifocal motor neuropathy (MMN) and multifocal acquired demyelinating sensory and motor (MADSAM) neuropathy, also known as Lewis-Sumner syndrome or multifocal chronic immune demyelinating polyradiculoneuropathy (CIDP), the presence ganglioside autoantibodies, particularly high-titer GM1-IgM autoantibodies, maybe supportive of the diagnosis in the correct clinical context. Furthermore, ganglioside seropositivity has been associated with favorable response to immunotherapy amongst patients suspected to have MMN during the initial clinical evaluation.(1)

 

Additionally, the presence of ganglioside antibodies may support a diagnosis of Guillain-Barre syndrome (GBS) in the appropriate clinical context.(3) GBS is one class of autoimmune peripheral neuropathies, and comprises a spectrum of disorders including acute inflammatory demyelinating polyradiculoneuropathy, acute motor axonal neuropathy, and acute motor and sensory axonal neuropathy. This class of autoimmune neuropathies is generally characterized by an acute onset. Although the diagnosis of these disorders is dependent on clinical evaluation and electrophysiologic studies, assessment of ganglioside antibodies can further support the diagnosis.

Reference Values

Only orderable as part of a profile. For more information see GM1B / Ganglioside Antibody Panel, Serum.

 

Negative

 

Reference values apply to all ages.

Interpretation

High titers (>1:8,000) favor the diagnosis of multifocal motor neuropathy (MMN) and multifocal acquired demyelinating sensory and motor (MADSAM) over motor neuron disease. About 30% to 50% of patients with these clinical syndromes or the pure motor variant of chronic inflammatory demyelinating polyneuropathy have ganglioside autoantibodies. High-antibody titers appear to be a specific, but not sensitive, marker of those related disorders.

Cautions

Positive titer values less than 1:16,000 may be found in motor neuron disease, monoclonal gammopathy of uncertain significance (MGUS), and healthy individuals. High titers are very specific of an autoimmune neuropathy.

 

This test is not diagnostic and should be interpreted in the appropriate clinical context.

 

This test does not include testing for GD1a or GQ1b autoantibodies.

Method Description

Antiganglioside antibodies in serum are detected by enzyme-linked immunosorbent assays (ELISA). Ganglioside antigens (GM1, Asialo GM1, and GD1b) adsorbed to wells of ELISA plates are incubated with patient's serum or controls. The plates are washed and alkaline phosphatase conjugated antihuman IgG or IgM antibodies (ie, secondary) are added in a second incubation. The wash step is repeated and enzyme substrate is added. Absorbance is measured and results are expressed as antibody titer, ie, the greatest dilution at which the absorbance of wells that contain patient serum is greater than 2.0 times the mean absorbance of normal sera tested simultaneously.(Taylor BV, Gross L, Windebank AJ: The sensitivity and specificity of anti-GM1 antibody testing. Neurology 1996 October;47:951-955)

Day(s) and Time(s) Performed

Tuesday, Thursday; 12 p.m.

Analytic Time

5 days

Specimen Retention Time

28 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

83516

LOINC Code Information

Test ID Test Order Name Order LOINC Value
IGG_M IgG Monos. GM1 43240-1

 

Result ID Test Result Name Result LOINC Value
4412 IgG Monos. GM1 43240-1