ITPR1 and neoplasm: In one of these patients [30], ITPR1-IgG was negative in the CSF on three occasions, including at disease onset, but reportedly temporarily positive once, and negative in the serum in four matched serum samples, ITPR1-specific binding of the patient’s IgG to brain tissue was not demonstrated, and the associated tumour did not express ITPR1, which in summary casts doubts on the diagnosis.