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HelpTest Code GBACS Gamma-Amino Butyric Acid Type A (GABA-A) Receptor Antibody by Cell Binding Assay, Serum
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Red top
Acceptable: SST
Submission Container/Tube: Plastic vial
Specimen Volume: 0.30 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Useful For
Evaluating patients with suspected autoimmune encephalitis and autoimmune epilepsy.
Method Name
Cell Binding Assay (CBA)
Reporting Name
GABA-A-R Ab CBA, SSpecimen Type
SerumSpecimen Minimum Volume
0.25 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
Gamma-amino butyric acid type A (GABA-A) receptor autoantibodies are highly predictive of GABA-A receptor autoimmune encephalitis. Seropositive GABA-A receptor encephalitis patients have characteristic clinical-radiologic presentations including frequent seizures and multifocal lesions in the white matter. Majority of patients are treatable with immunotherapy.
Reference Values
Negative
Interpretation
Seropositivity for gamma-amino butyric acid type A receptor autoantibodies supports the clinical diagnosis of autoimmune encephalitis with neurological presentations including seizures and multifocal lesions in the white matter. A search for thymoma cancer, and a trial of immunotherapy should be considered.
Cautions
Negative results do not exclude the diagnosis of autoimmune encephalitis. Only 2% of cases of autoimmune encephalitis are associated with autoantibodies against gamma-amino butyric acid type A receptor.
Method Description
Patient specimen is applied to a composite slide containing transfected and nontransfected HEK-293 cells. After incubation and washing, fluorescein-conjugated goat-antihuman IgG is applied to detect the presence of patient IgG binding.(Package insert: IIFT: Neurology Mosaics, Instructions for the indirect immunofluorescence test. EUROIMMUN, FA_112d-1_A_UK_C13, 02/2019)
Day(s) Performed
Monday through Sunday
Report Available
5 to 10 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
86255
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| GBACS | GABA-A-R Ab CBA, S | 101874-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 620232 | GABA-A-R Ab CBA, S | 101874-6 |