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HelpTest Code GQ1ES Ganglioside GQ1b Antibody, IgG, ELISA, Serum
Necessary Information
Provide the following information:
1. Relevant clinical information
2. Ordering provider name, phone number, mailing address, and email address
Specimen Required
Patient Preparation: For optimal antibody detection, specimen collection is recommended to occur prior to initiation of immunosuppressant medication or intravenous immunoglobulin treatment.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Useful For
Evaluating patients with an underlying demyelinating neuropathy
Supporting the diagnosis of a ganglioside GQ1b IgG-related disorder
Method Name
Enzyme-Linked Immunosorbent Assay (ELISA)
Reporting Name
GQ1b-IgG ELISA, SSpecimen Type
SerumSpecimen 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
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.
Reference Values
Negative
Interpretation
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.
Cautions
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.
Method Description
Microwells are precoated with ganglioside GQ1b antigen. The calibrator, controls, and diluted patient samples are added to the wells, and autoantibodies recognizing GQ1b bind during the first incubation. After washing the wells to remove all unbound proteins, purified horseradish peroxidase-labeled anti-human IgG conjugate is added. The conjugated IgG binds to the captured human autoantibody, and the excess unbound conjugated IgG is removed by a further wash step. The bound conjugated IgG is visualized with 3,3',5,5'-tetramethylbenzidine substrate, which gives a blue reaction product, the intensity of which is proportional to a concentration of autoantibody in the sample. Acid is added to each well to stop the reaction. This produces a yellow end-product color, which is read at 450 nm. Patient results are calculated as a cutoff index (COI) by dividing the optical density (OD) of patient sera or controls by the average OD of the calibrator. Any sample with a COI greater than or equal to 1.0 is considered positive. Any sample with a COI less than 1.0 is considered negative. Results are reported qualitatively as positive or negative.(Unpublished Mayo method)
Day(s) Performed
Monday, Wednesday, Friday
Report Available
5 to 8 daysPerforming 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. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
83516
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| GQ1ES | GQ1b-IgG ELISA, S | 63254-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 621107 | GQ1b-IgG ELISA, S | 63254-7 |