NMDA (Anti-glutamate receptor (Type NMDA) antibodies)
Anti-NMDA receptor encephalitis manifests along a spectrum of psychosis, altered behaviour, movement disorder, seizures, autonomic dysfunction and decreased consciousness. In younger patients, particularly female, it is associated with an underlying teratoma. Early identification and treatment with immunotherapy leads to better outcomes (Pubmed ID 23290630). It is less common in older patients (over 45 years old) and they display a less severe phenotype and have poorer outcomes (Pubmed ID23946310).
Antibodies against the NR1 subunit of the NMDA receptor are identified in our laboratory via indirect immunofluorescence of cell lines transfected with cDNA coding this protein. This test has very high positive and negative predictive values. Testing is carried out on serum or CSF. CSF is preferred for testing since there are fewer false positives or false negatives compared with serum.