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Test Code AK5CC Adenylate Kinase 5 (AK5) IgG, Cell Based Assay, Spinal Fluid (Non-Orderable)


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


Secondary ID

623400

Useful For

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

 

Evaluation of patients suspected to have autoimmune encephalitis using spinal fluid specimens

 

Reporting adenylate kinase 5 IgG results as part of a profile

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

 

Cell Binding Assay (CBA)

Reporting Name

AK5 Ab CBA, CSF

Specimen Type

CSF

Specimen Minimum Volume

1.5 mL

Specimen Stability Information

Specimen Type Temperature Time
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

Adenylate kinase 5 IgG (AK5-IgG) is a marker intended for evaluating patients with autoimmune encephalitis, most often presenting as a non-paraneoplastic limbic encephalitis. Poor response to immunotherapy has been reported while there is no clear cancer association (non-paraneoplastic). AK5-IgG positive patients present with predominant severe amnestic syndrome, associated depression, and anxiety. Epilepsy is often absent at disease onset, however seizures may develop later.

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

 

Negative

Interpretation

A positive result is consistent with adenylate kinase 5 autoimmunity that manifests with non-paraneoplastic limbic encephalitis.

Cautions

A negative result does not exclude the diagnosis of autoimmune encephalitis.

Clinical Reference

1. Muuiz-Castrillo S, Hedou JJ, Ambati A, et al. Distinctive clinical presentation and pathogenic specificities of anti-AK5 encephalitis. Brain. 2021;144(9):2709-2721. doi:10.1093/brain/awab153

2. McKeon-Makki I, McKeon A, Yang B, et al. Adenylate kinase 5 (AK5) autoimmune encephalitis: Clinical presentations and outcomes in three new patients. J Neuroimmunol. 2022;367:577861. doi:10.1016/j.jneuroim.2022.577861

3. Honorat JA, Lopez-Chiriboga AS, Kryzer TJ, et al. Autoimmune gait disturbance accompanying adaptor protein-3B2-IgG. Neurology. 2019;93(10):e954-e963. doi:10.1212/WNL.0000000000008061

Method Description

Patient specimen is applied to a composite slide containing transfected and non-transfected human embryonic kidney (HEK293) cells. After incubation and washing, fluorescein-conjugated goat-antihuman IgG is applied to detect the presence of patient IgG binding.(Unpublished Mayo method)

Day(s) Performed

Varies

Report Available

5 to 10 days

Specimen Retention Time

2 days

Performing 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
AK5CC AK5 Ab CBA, CSF In Process

 

Result ID Test Result Name Result LOINC Value
623400 AK5 Ab CBA, CSF In Process