Patients with stiff-person syndrome, progressive encephalomyelitis with rigidity and myoclonus (PERM), or cerebellar ataxia associated with breast cancer or small cell lung cancer (SCLC) have antibodies against one or more proteins of GABAergic or glycinergic synapses, including glutamic acid decarboxylase 65 (GAD65), the glycine receptor (GlyR), or amphiphysin [26,27,28,29]. The gene discussed is GAD2; the disease is small cell lung carcinoma.