ITPR1 and Ataxia: Including the case described in Section A, 21 patients with serum antibodies to ITPR1 and central and peripheral neurological symptoms have been described in the literature so far (and at least 10 further patients have been identified in historic series of samples with anti-PC antibodies but not yet published due to the sparsity of available clinical data [4, 18]):In 2014, we reported on ITPR1-IgG/anti-Sj in a woman with a 10-year history of progressive ataxia of the upper limbs, dysarthria, and gaze disturbances.