Mouse brain tissue lysates were immunoprecipitated with protein A/G Sepharose beads which had been incubated with serum from patient or control participant. The immune complexes were subsequently separated by SDS‒PAGE. Bands were excised from the gel, and trypsin-digested samples were subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS) using an Orbitrap Velos Pro (Thermo Scientific). MS/MS dataset analysis was performed using the Mascot software program (Matrix Science).