Read Anti-NMDA Receptor (NR1) IgG Antibodies text version

NATIONAL REFERENCE LABORATORY

Anti-NMDA Receptor (NR1) IgG Antibodies

FoR DiAgNosis oF Limbic eNcePhALitis

Test Highlights

Anti-NMDAreceptorautoantibodiesarespecificmarkersforanti-NMDAreceptorencephalitis.

Clinical Background

· TheN-methyl-D-aspartatereceptor(NMDAR)isanionchannel located in the post-synaptic membrane that plays a key role in synaptictransmissionandplasticity.Thereceptorismadeupof twosubunits,NR1andNR2,thatcontainextracellularepitopes. Anti-NMDAR antibodies are directed against the extracellular epitopeoftheNR1subunit. · This test is a cell-based indirect immunofuorescence antibody (IFA) assay for anti-NR1, which is strongly associated with treatment-responsivelimbicencephalitis. · Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is aninflammatoryencephalopathicautoimmunediseasefrequently affecting young women with teratomas of the ovary. It is also observedinmen,children,andfemaleswithouttumors. · Teratomasoftheovaryareusuallybenign.Alsocalleddermoid cysts,teratomasoftheovarycharacteristicallycontainadiversity oftissuessuchashair,teeth,bone,thyroid,andneuraltissue. · Prodomalsymptomsofanti-NMDARencephalitisincludelowgrade fever, headache, and non-specific viral-like illness. Once thediseasereachesthepsychoticstage,symptomsinclude: Visualorauditoryhallucinations Delusions Severebehavioralandpersonalitychanges(memoryproblems) Paranoidthoughts Unresponsiveness(decreasedconsciousness) Seizures(epilepticattacks) Dyskinesia,movementdisorders Autonomousinstability Cardiacdysrhythmias Centralhypoventilation · The symptoms of this form of encephalitis are very similar to thoseofotherconditions;itisthereforedifficulttodeterminethe prevalenceofthisdisorder.

· A positive result showing the presence of anti-NMDAR antibodiesinserumisstronglysupportiveofadiagnosisofantiNMDARencephalitis. · In a positive serological event in a female, a full teratoma investigationshouldbecarriedout. · AnegativeresultindicatestheabsenceofNMDARencephalitis, butneuropiliccoloringofrathippocampusandcerebellumcan alsopointtothepresenceofotherautoantibodiesassociatedwith limbicencephalitis(e.g.,anti-VGKCantibodiesandanti-AMPA receptorantibodies). · Thereisareductionandpossibledisappearanceofantibodytiter withclinicalimprovement. · Other forms of limbic encephalitis, vasculitis, and infectious encephalomeningitis need to be included in the differential diagnosis.

Methodology

The presence of anti-NMDAR antibodies in serum is detected by IFA using a human cell line (Hek293) transfected with the NR1 receptorsubunit.

Related Tests

Inadditiontotestingserum,ananalogousinvestigationofCSFcan alsobeofgreatimportance,asintrathecalsynthesisofanti-NMDAR antibodiesisfrequentandmayonlybedetectedinCSF.BrainMRI and EEG analysis can also support diagnosis if necessary. Other autoantibodiesassociatedwithlimbicencephalitis,suchasHuand amphiphysin,mayalsobeofadditionaldiagnosticvalue.

References

1. Dalmau J, et al. Anti-NMDA-receptor encephalitis: case series and analysis of the effects of antibodies. Lancet Neurol 2008;7(12):1091­8. 2. VincentA,BienCG.Anti-NMDA-receptorencephalitis:acause ofpsychiatric,seizure,andmovementdisordersinyoungadults. Lancet Neurol2008;7:1074­5. 3. Prüss H, et al. Anti-NMDA-receptor encephalitis. An interdisciplinary clinical picture. Nervenarzt 2010;81(4):396, 398,400. 4. Tüzün E, Dalmau J. Limbic encephalitis and variants: classification, diagnosis and treatment. Neurologist 2007;13(5):261­71.

Indications for Ordering

This test is indicated for patients with suspected anti-NMDAR encephalitis.

Interpretation

· Diagnosisofanti-NMDARencephalitisdependsonthepresence of the characteristic clinical picture, supporting results from brainmagneticresonanceimaging(MRI),electroencephalogram (EEG),andcerebrospinalfluid(CSF),andthedetectionofantiNMDAreceptorantibodiesinserumorCSF.

©2010 ARUP LABORATORIES. ALL RIGHTS RESERVED. NOVEMBER 2010

500 Chipeta Way, Salt Lake City, UT 84108 | (800) 522-2787 | (801) 583-2787 | www.aruplab.com | www.arupconsult.com

ARUP is an enterprise of the University of Utah and its Department of Pathology.

Test Information

2004221 N-methyl-D-AspartateReceptorAntibody,IgG

Forspecificcollection,transport,andtestinginformation,refertotheARUPwebsiteatwww.aruplab.com. Forinformationontestselection,ordering,andinterpretation,refertoARUPConsult®atwww.arupconsult.com.

ARUP LABORATORIES | NOVEMBER 2010

Information

Anti-NMDA Receptor (NR1) IgG Antibodies

2 pages

Find more like this

Report File (DMCA)

Our content is added by our users. We aim to remove reported files within 1 working day. Please use this link to notify us:

Report this file as copyright or inappropriate

62401