First, no banked serum prevented cell-based assays (CBA) for neuronal surface antibodies (e.g., anti-GABABR, anti-AMPAR1/2) and anti-SOX1 serology; P/Q-type VGCC testing to exclude subclinical LEMS/ataxia was not possible. Here, SOX1 is linked to Lambert-Eaton myasthenic syndrome.