GRM1 and neoplasm: Rare NSAS (with antibodies targeting D2R, GABAAR, GlyR, GABABR, AMPAR, amphiphysin, mGluR5, mGluR1, DPPX, IgLON5, and neurexin-3alpha): main distinctive features in paediatric age compared to adults, as regards demographics, clinical features and association with tumour, based on our systematic literature review and on previous literature observations (3, 4, 23, 36, 66–68).