Test ID: MDS2    
Movement Disorder, Autoimmune Evaluation, Serum

Evaluating patients with suspected paraneoplastic or other autoimmune movement disorders including patients with ataxia, chorea, dyskinesias, myoclonus, parkinsonism, and stiff-person spectrum in serum specimens

If immunofluorescence assay (IFA) pattern suggests amphiphysin antibody, then amphiphysin immunoblot is performed at an additional charge.

If IFA pattern suggests antiglial nuclear antibody-1 (AGNA)-1, then AGNA-1 immunoblot is performed at an additional charge.

If IFA pattern suggests antineuronal nuclear antibodies (ANNA)-1, then ANNA-1 immunoblot is performed at an additional charge.

If IFA pattern suggests ANNA-2 antibody, then ANNA-2 immunoblot is performed at an additional charge.

If IFA pattern suggests Purkinje cytoplasmic antibody (PCA-1), then PCA-1 immunoblot is performed at an additional charge.

If IFA pattern suggests PCA-Tr antibody, then PCA-Tr immunoblot is performed at an additional charge.

If IFA pattern suggests IgLON5 antibody, then IgLON5 cell-binding assay (CBA) and IgLON5 titer are performed at an additional charge.

If IFA pattern suggests GTPase regulator associated with focal adhesion kinase-1 (GRAF1) antibody, then GRAF1 CBA and GRAF1 titer are performed at an additional charge.

If IFA pattern suggests inositol 1,4,5-trisphosphate receptor (ITPR1) antibody, then ITPR1 CBA and ITPR1 titer are performed at an additional charge.

If IFA pattern suggests alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-receptor antibody, then AMPA-receptor cell-binding assay (CBA) and AMPA-receptor titer are performed at an additional charge.

If IFA pattern suggests dipeptidyl-peptidase-like protein-6 antibody (DPPX) antibody, then DPPX CBA and DPPX titer are performed at an additional charge.

If IFA pattern suggests gamma-aminobutyric acid B (GABA-B)-receptor antibody, then GABA-B-receptor CBA and GABA-B-receptor titer are performed at an additional charge.

If IFA pattern suggests metabotropic glutamate receptor 1 (mGluR1) antibody, then mGluR1 CBA and mGluR1 titer are performed at an additional charge.

If IFA pattern suggests N-methyl-D-aspartate (NMDA)-receptor antibody and NMDA-receptor CBA is positive, then NMDA-receptor titer is performed at an additional charge.

If IFA pattern suggests neuronal intermediate filament (NIF) antibody, then alpha internexin CBA, NIF heavy chain CBA, NIF light chain CBA, and NIF titer are performed at an additional charge.

See Movement Disorder Autoimmune Evaluation Algorithm-Serum in Special Instructions.

Autoimmune movement disorders encapsulate a large and diverse group of neurologic disorders occurring either in isolation or accompanying more diffuse autoimmune encephalitic illnesses.

The full range of movement phenomena has been described and, as they often occur in adults, many of the presentations can mimic neurodegenerative disorders, such as autoimmune chorea mimicking Huntington disease. Disorders may be ataxic, hypokinetic (parkinsonism), or hyperkinetic (myoclonus, chorea other dyskinetic disorders).

The autoantibody targets are diverse and include neuronal surface proteins such as leucine-rich, glioma-inactivated 1 (LGI1), as well as antibodies reactive with intracellular antigens (such as Purkinje cell cytoplasmic antibody-1: PCA-1) that are markers of a central nervous system process mediated by CD8+ cytotoxic T cells.

In some instances (such as PCA-1 autoimmunity), antibodies detected in serum and cerebrospinal fluid can be indicative of a paraneoplastic cause, and may direct the cancer search. In other instances (such as 65kDa isoform of glutamic acid decarboxylase: GAD65 autoimmunity), a paraneoplastic cause is very unlikely, and early treatment with immunotherapy may promote improvement or recovery.

Reflex Information:

Neuron-restricted patterns of IgG staining that do not fulfill criteria for ANNA-1, ANNA-2, CRMP-5-IgG, PCA-1, PCA-2, or PCA-Tr may be reported as "unclassified anti-neuronal IgG." Complex patterns that include nonneuronal elements may be reported as "uninterpretable."

A positive antibody result is consistent with a diagnosis of an autoimmune movement disorder.

A search for cancer may be indicated, depending on the antibody profile.

A trial of immune therapy may bring about improvement in neurological symptoms.

A negative antibody test result does not exclude an autoimmune movement disorder.

Corticosteroid treatment prior to the serum collection may cause a false-negative result.

Intravenous immunoglobulin (IVIg) treatment prior to the serum collection may cause a false-positive result.

1. Honorat JA, McKeon A: Autoimmune Movement Disorders: a Clinical and Laboratory Approach. Curr Neurol Neurosci Rep. 2017 Jan;17(1):4. doi: 10.1007/s11910-017-0709-2

• Movement Disorder Autoimmune Evaluation Algorithm-Serum