Expanding the clinical spectrum of anti‐IgLON5 disease: A multicenter retrospective study

Abstract Background We conducted this study to describe detailed the clinical characteristics, ancillary test results and treatment response of a group of Chinese patients with anti‐IgLON5 disease. Methods We recruited 13 patients with positive IgLON5 antibodies in serum and/or cerebrospinal fluid from nine tertiary referral centers. Patients were enrolled from February 2017 to July 2021. We retrospectively collected information on the presenting and main symptoms, treatment response and follow‐up outcomes. Results The median age of onset for symptoms was 60 (range: 33–73) years and six of the 13 patients were females. The predominant clinical presentations included sleep disturbance (eight patients) and cognitive impairment (seven patients), followed by movement disorders (six patients). Parainfectious cause seemed plausible. Notably, we identified the first case of possible Epstein‐Barr virus (EBV)‐related anti‐IgLON5 disease. Coexisting neural autoantibodies were identified in two patients. Furthermore, two patients had other autoimmune diseases. The IgG subclass was determined in four patients, including two with dominant IgG4 subtype and two with dominant IgG1 subtype. Additionally, 10 patients were treated with immunotherapy and four patients exhibited improvement. Overall, six of 10 patients for whom follow‐up results were assessable had favorable clinical outcomes (modified Rankin Scale score ≤2). Conclusions The clinical spectrum of anti‐IgLON5 disease is variable. Our results highlight a boarder spectrum of anti‐IgLON5 disease.