Ordering Recommendation

Aids in the diagnosis of limbic encephalitis and autoimmune epilepsy. May be used to monitor treatment response in individuals who are antibody positive. The presence of GABA-AR antibodies may be associated with refractory seizures, memory loss, behavior changes, abnormal movements, and decreased level of consciousness. GABA-AR encephalitis may be paraneoplastic, but tumor type is variable (eg, thymoma, small cell lung cancer, rectal cancers, and hematologic malignancy). GABA-AR encephalitis may also be associated with post-viral and autoimmune diseases.

Mnemonic

GABA-A CSF

Methodology

Semiquantitative Cell-Based Indirect Fluorescent Antibody

Performed

Wed

Reported

1-8 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

CSF.

Specimen Preparation

Transfer 0.5 mL CSF to an ARUP standard transport tube. (Min: 0.15 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Grossly hemolyzed or contaminated specimens.

Remarks
Stability

Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 month (Three freeze/thaw cycles are acceptable)

Reference Interval

Less than 1:1

Interpretive Data

Gamma-aminobutyric acid receptor, type A (GABA-AR) antibody is found in a subset of patients with autoimmune encephalitis or autoimmune epilepsy and may occur with or without an associated tumor. A negative test result does not rule out a diagnosis of autoimmune limbic encephalitis or autoimmune epilepsy. Interpretation of any antineural antibody test requires clinical correlation.

This indirect fluorescent antibody assay utilizes GABA-AR transfected cell lines for detection and semiquantification of GABA-AR IgG antibody.

Compliance Category

Laboratory Developed Test (LDT)

Note

If GABA-AR antibody IgG is positive, then GABA-AR antibody IgG titer will be added. Additional charges apply.

Hotline History

N/A

CPT Codes

86255; if reflexed, add 86256

Components

Component Test Code* Component Chart Name LOINC
3006004 GABA-AR Ab IgG CBA-IFA Screen, CSF
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.

Aliases

  • autoimmune encephalitis
  • autoimmune epilepsy
  • encephalopathy
  • GABA-A
  • Limbic encephalitis
Gamma-Aminobutyric Acid Receptor, Type A (GABA-AR) Antibody, IgG by CBA-IFA with Reflex to Titer, CSF