26636 Ganglioside GQ1b Antibody, IgG, ELISA, Serum (GQ1ES)

GQ1b-IgG ELISA

Evaluating patients with an underlying demyelinating neuropathy

Supporting the diagnosis of a ganglioside GQ1b IgG-related disorder

Patient Preparation: For optimal antibody detection, specimen collection is recommended to occur prior to initiation of immunosuppressant medication or intravenous immunoglobulin treatment.

Centrifuge and aliquot serum into a plastic vial.

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Provide the following information:

1. Relevant clinical information

2. Ordering provider name, phone number, mailing address, and email address

Gross hemolysis, gross lipemia, gross icterus

A negative result does not exclude the presence of disease. The use of immunotherapy prior to specimen collection may negatively impact the sensitivity of this assay.

Testing for ganglioside GQ1b antibodies should be performed near the onset of disease.

​This test should be interpreted in the appropriate clinical context.

​Ganglioside GQ1b antibody (GQ1b IgG) is a biomarker for a group of related disorders that includes Miller Fisher syndrome (MFS), Bickerstaff brainstem encephalitis (BBE), and classic Guillain–Barre syndrome (GBS) with ophthalmoplegia. Collectively, these are referred to GQ1b IgG-related syndromes. The prevalence of GQ1b IgG in this population of patients is high and has been reported to be greater than 80% in well-defined clinical cohorts. In classic GBS, the prevalence of GQ1b IgG positivity is low but has been reported in the literature. Patients with GQ1b IgG-related disorders may not require immunotherapy, presumably because they have a good prognosis and spontaneous recovery. In severe cases, both intravenous immunoglobulin (IVIG) and plasma exchange are effective treatments for MFS and BBE. In patients with a clinical suspicion of MFS and related disorders, positivity for GQ1b IgG supports the specific clinical diagnosis and may also provide prognostic information. Although the diagnosis of these disorders is dependent on clinical evaluation and electrophysiologic studies, assessment of GQ1b IgG can further support the diagnosis. 

Negative

A positive result is consistent with an immune-mediated demyelinating neuropathy and correlation with clinical electrodiagnostic features is recommended.

Ganglioside GQ1b (GQ1b) IgG antibodies occur in Miller Fisher syndrome, Bickerstaff brainstem encephalitis, and atypical Guillain-Barre syndromes having variably present demyelinating neuropathy, ophthalmoplegia, ataxia, brainstem features with encephalitis and, less commonly, other neurogenic conditions.

A negative result does not exclude an immune-mediated demyelinating neuropathy nor a GQ1b IgG syndrome.