To describe temporal trends, positivity rates and antibody spectrum identified through neural antibody testing at a single tertiary academic centre in Singapore.
Autoimmune encephalitis and paraneoplastic neurological disorders are treatable but readily missed when antibody testing is limited. In Southeast Asia, locally available commercial cell-based assays cover a narrow antibody subset, and the disease spectrum detectable through comprehensive panel testing has not been systematically described.
Retrospective review of patients who underwent neural antibody testing at the National University Hospital, Singapore between 1 January 2018 and 31 December 2024. Patients included had standalone NMDAR cell-based assay (CBA) locally, and/or paraneoplastic (PNEO) and autoimmune encephalopathy (ENC) panels at the Mayo Clinic Neuroimmunology Laboratory. Patients tested only for AQP4 and MOG were excluded.
Of 1465 patients tested, 925 met inclusion criteria (median age 51 years, IQR 17-67; 53% female; Chinese 67.9%, Malay 13.1%, Indian 7.5%, others 11.5%). A total of 2168 neural antibody tests were performed: 1278 panels (1125 ENC, 153 PNEO), and 890 CBAs (performed locally or via separate referral for NMDAR, glycine receptor, AQP4, MOG); 513 of 751 panel-tested patients (68%) had paired serum and CSF. Ninety patients (9.7%) had clinically significant seropositivity, spanning nineteen distinct neural antibodies. The most frequent were NMDAR (n=29), VGCC P/Q-type (n=15), GFAP (n=8), GABA-B (n=7), LGI1 (n=7) and high titre GAD65 (n=6); rarer antibodies included mGluR1, IgLON5, AP3B2, and AMPAR. Seventeen patients (18.9%) had two or more coexisting antibodies.
Comprehensive testing in this seven-year multi-ethnic Southeast Asian cohort identified a diverse neural antibody spectrum, including rarer antibodies undetectable by currently available commercial assays. These findings suggest the apparent rarity of certain antibody-mediated neurological disorders in this region may reflect limits of regional testing rather than true differences in disease frequency and support a broadened approach to antibody evaluation in patients with suspected autoimmune neurological disease.