Indirect evidence suggesting a potential pathogenic role of anti-ITPR1 includes the fact that the antibodies mainly belonged to the complement-activating IgG1 subclass, the very high serum titres in two of our patients (titres were lower in patient 2, in whom ITPR1 was tested late in the disease course), the decline in titres after tumour removal, which was accompanied by clinical stabilization and improvement, and the good concordance of the antigen’s tissue expression profile with the clinical symptoms present in our patient, in particular in patient 1. Here, ITPR1 is linked to neoplasm.