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HelpTest Code APHTC Amphiphysin Antibody Titer Assay, Spinal Fluid
Ordering Guidance
Serum is preferred. Spinal fluid testing is particularly useful if interfering antibodies are present in the serum.
Specimen Required
Only orderable as a reflex. For more information see:
-DMC2 / Dementia, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-ENC2 / Encephalopathy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-EPC2 / Epilepsy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-MDC2 / Movement Disorder, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-MAC1 / Myelopathy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-SPPC / Stiff-Person Spectrum Disorders Evaluation, including Progressive Encephalomyelitis with Rigidity and Myoclonus, Spinal Fluid
Container/Tube: Sterile vial
Specimen Volume: 4 mL
Useful For
Evaluating patients with recent onset of a subacute neurological disorder for which a paraneoplastic basis might be suspected, particularly if the patient has a previous history, risk factors, or family history of cancer, especially lung or breast cancer
Reporting an end titer result from cerebrospinal fluid specimens
Testing Algorithm
If the indirect immunofluorescence pattern suggests amphiphysin antibody, then this test will be performed at an additional charge.
Method Name
Only orderable as a reflex. For more information see:
-DMC2 / Dementia, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-ENC2 / Encephalopathy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-EPC2 / Epilepsy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-MDC2 / Movement Disorder, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-MAC1 / Myelopathy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-SPPC / Stiff-Person Spectrum Disorders Evaluation, including Progressive Encephalomyelitis with Rigidity and Myoclonus, Spinal Fluid
Indirect Immunofluorescence Assay (IFA)
Reporting Name
Amphiphysin Ab Titer, CSFSpecimen Type
CSFSpecimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| CSF | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Clinical Information
Antineuronal autoantibodies specific for amphiphysin (a 128-kDa synaptic vesicle-associated protein) are found in a paraneoplastic context. These IgG antibodies were initially described as a serological marker of paraneoplastic stiff-man syndrome associated with breast carcinoma. They are now more aptly recognized as a marker of autoimmune encephalomyeloneuritis, sensory neuronopathy, and assorted neuromyopathic disorders associated with small-cell lung carcinoma or breast carcinoma.
Only 1 of 30 patients identified as seropositive for amphiphysin antibodies in the Mayo Clinic Neuroimmunology Laboratory exhibited any stiff-person phenomena (n=63: 39% women, 12% men). Only 10% of women (some with lung carcinoma) and 4% of men fulfilled diagnostic criteria for stiff-man syndrome. Overall, cancer was detected in 79.4% of seropositive patients (at last follow-up). Lung carcinoma (small cell) accounted for 61% of cancers and 35% had breast carcinoma (42% for women).
Amphiphysin seropositivity implicates antineuronal autoimmunity as the basis for a variety of neurological presentations and focuses the patient's subsequent investigation to a search for breast carcinoma or small-cell lung carcinoma.
Reference Values
Only orderable as a reflex. For more information see:
-DMC2 / Dementia, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-ENC2 / Encephalopathy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-EPC2 / Epilepsy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-MDC2 / Movement Disorder, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-MAC1 / Myelopathy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid
-SPPC / Stiff-Person Spectrum Disorders Evaluation, including Progressive Encephalomyelitis with Rigidity and Myoclonus, Spinal Fluid
<1:2
Neuron-restricted patterns of IgG staining that do not fulfill criteria for amphiphysin antibody may be reported as "unclassified antineuronal IgG." Complex patterns that include nonneuronal elements may be reported as "uninterpretable."
Interpretation
Positive results are consistent with neurologic autoimmunity; usually related to breast carcinoma or small-cell lung carcinoma.
Cautions
Nonorgan-specific autoantibodies in high titer preclude identification of amphiphysin IgG by indirect immunofluorescence; Western blot assay should be done in those cases.
Method Description
The patient's sample is tested by a standardized immunofluorescence assay that uses a composite frozen section of mouse cerebellum, kidney, and gut tissues. After incubation with sample and washing, fluorescein-conjugated goat-antihuman IgG is applied. Neuron-specific autoantibodies are identified by their characteristic fluorescence staining patterns. Samples that are scored positive for any neuronal nuclear or cytoplasmic autoantibody are titrated to an endpoint. Interference by coexisting non-neuron-specific autoantibodies can usually be eliminated by serologic absorption.(Honorat JA, Komorowski L, Josephs KA, et al: IgLON5 antibody: neurological accompaniments and outcomes in 20 patients. Neurol Neuroimmunol Neuroinflamm 2017 Jul 18;4(5):e385. doi: 10.1212/NXI.0000000000000385)
Day(s) Performed
Monday through Sunday
Report Available
6 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
86256
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| APHTC | Amphiphysin Ab Titer, CSF | 94354-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 618164 | Amphiphysin Ab Titer, CSF | 94354-8 |