Anti-glutamate kainate receptor subunit 2 autoimmune encephalitis: a multicentre retrospective study

Background : The pathogenic role of the anti-glutamate kainate receptor subunit 2 (GluK2) antibodies in autoimmune encephalitis has been is well established. However, the clinical features in patients with these antibodies remain poorly understood. Therefore, we conducted a retrospective cohort study of Chinese patients with anti-GluK2 encephalitis. Methods : Between January 2023 and July 2024, we enrolled 10 patients with serum and/or cerebrospinal fluid (CSF) anti-GluK2 antibodies from four medical centres. We assessed data regarding symptoms, autoantibody testing, ancillary examinations, treatments, and outcomes. Results : The study cohort consisted of four male and six female participants. The mean age at onset was 47.5 ± 28.1 years (range: 14–85 years), with no significant gender difference observed ( p > 0.05). Primary clinical manifestations included altered consciousness (6/10), cognitive impairment (6/10), epileptic seizures (5/10), cerebellar ataxia (2/10), headache (2/10), extrapyramidal symptoms (2/10), limb weakness (2/10), and psychiatric and behavioural abnormalities (1/10). All patients were free from neoplastic lesions. One patient was positive for both serum and CSF anti-GluK2 antibodies, whereas eight showed positivity exclusively in serum; one patient lacked CSF information. Abnormal brain magnetic resonance imaging results were observed in four patients. In the acute phase, six patients received hormonal treatment. One patient received an immunoglobulin injection, whereas another received efgartigimod. During remission, rituximab was administered to one patient, and mycophenolate mofetil was prescribed to three. Seven patients recovered, one partially recovered, and one died from coronary heart disease, whereas another with sepsis was transferred to the neurological intensive care unit. Conclusion : Anti-GluK2 encephalitis is unlikely to be tumour-related. The prognosis for patients with anti-GluK2 antibodies appears favourable but remains uncertain. Anti-GluK2 encephalitis has heterogeneous symptoms; thus, evaluation of anti-GluK2 antibodies in serum and CSF from patients with suspected autoimmune encephalitis should be included.